ALT Attribute with <A HREF> - please check

Good day

i tried to validate http://www.fremo.org/service/angebo_d.htm
(The text is in German)

I got following result:

quote
Below are the results of attempting to parse this document with an SGML
parser. 

Line 64, column 43: there is no attribute "ALT" (explain...). 
  <a href="../module/images/alubein.jpg" alt="Foto eines Flansches"
                                             ^
Line 66, column 4: duplicate specification of attribute "ALT" (explain...).
unquote

The code of the two lines in question reads:
quote
<tr><td>Flansche, 10 cm für hohe Modulkasten<br>
<a href="../module/images/alubein.jpg" alt="Foto eines Flansches"
target="bein"
ALT='Foto eines Flansches' >Foto</a></td><td>Paar</td><td>5,50 EUR</td></tr>
unquote

I intentionally put the second 'ALT' into the code, as the validator
kept complained about the missing one and now i got this illogical result.

As this is no inline image, but a link to an external image
with is described in the text I think the ALT attribute is
not necessary in this context and should be omitted altogether.

Would like to receive your opinion

Carsten Moeller
mailto:webmaster@fremo.org
Hamburg Germany