Hallo Matze,
bitte korrigiere erst einmal alle Fehler in deiner Seite. Dann lass uns schauen, ob der Fehler immer noch vorhanden ist. Wenn du die Seite online stellen könntest wäre das noch viel besser. So kommen wir erst einmal nicht weiter.
----------- VALIDATOR-ERGEBNISSE --------------------
http://validator.w3.org/
This page is not Valid HTML 4.01 Transitional!
Below are the results of attempting to parse this document with an SGML parser.
Line 12, column 37: there is no attribute "HEIGHT"
<table border="0" width="800" height="0" cellspacing="0" cellpadding="0">
You have used the attribute named above in your document, but the document type you are using does not support that attribute for this element. This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute), or by using vendor proprietary extensions such as "marginheight" (this is usually fixed by using CSS to achieve the desired effect instead).
This error may also result if the element itself is not supported in the document type you are using, as an undefined element will have no supported attributes; in this case, see the element-undefined error message for further information.
How to fix: check the spelling and case of the element and attribute, (Remember XHTML is all lower-case) and/or check that they are both allowed in the chosen document type, and/or use CSS instead of this attribute.
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Line 13, column 11: there is no attribute "HEIGHT"
<tr height="0">
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Line 37, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
An "id" is a unique identifier. Each time this attribute is used in a document it must have a different value. If you are using this attribute as a hock for style sheets it may be more appropriate to use classes (which group elements) than id (which are used to identify exactly one element).
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Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 40, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
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Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 43, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
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Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 44, column 13: ID "NAV-LEFT" already defined
<td id=nav-left><a href="sen.html">Senertec</a></td>
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Line 33, column 13: ID "NAV-LEFT" first defined here
<td id=nav-left> </td>
Line 45, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
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Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 48, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
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Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 49, column 13: ID "NAV-LEFT" already defined
<td id=nav-left><a href="pho.html">Photovoltaik</a></td>
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Line 33, column 13: ID "NAV-LEFT" first defined here
<td id=nav-left> </td>
Line 50, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
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Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 53, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
✉
Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 54, column 13: ID "NAV-LEFT" already defined
<td id=nav-left><a href="was.html">Wasserkraft</a></td>
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Line 33, column 13: ID "NAV-LEFT" first defined here
<td id=nav-left> </td>
Line 55, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
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Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 57, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
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Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 58, column 13: ID "NAV-LEFT" already defined
<td id=nav-left><a href="sch.html">Schaltanlagen</a></td>
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Line 33, column 13: ID "NAV-LEFT" first defined here
<td id=nav-left> </td>
Line 59, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
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Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 62, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
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Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 63, column 13: ID "NAV-LEFT" already defined
<td id=nav-left><a href="kon.html">Kontakt</a></td>
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Line 33, column 13: ID "NAV-LEFT" first defined here
<td id=nav-left> </td>
Line 64, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
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Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 67, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
✉
Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
Line 68, column 13: ID "NAV-LEFT" already defined
<td id=nav-left> </td>
✉
Line 33, column 13: ID "NAV-LEFT" first defined here
<td id=nav-left> </td>
Line 69, column 13: ID "NAV-RIGHT" already defined
<td id=nav-right> </td>
✉
Line 34, column 13: ID "NAV-RIGHT" first defined here
<td id=nav-right> </td>
Line 72, column 13: ID "NAV-BORDER" already defined
<td id=nav-border> </td>
✉
Line 32, column 13: ID "NAV-BORDER" first defined here
<td id=nav-border> </td>
--------- VALIDTAOR ENDE --------------
Mit freundlichen Grüßen
André