yep, I resolved the problem with an invalid RSS address. The solution is, to edit plugin in a wordpress.

You can find the line:
<input id="url" name="flickrcommenturl" type="text" size="85" maxlength="300" value="” style=”font-family: ‘Courier New’, Courier, mono; font-size: 1.5em;” />

and normally – the value of “maxlength” was set to 100, which is invalid for long flickr addresses. I changed it to 300, and works well.