can't get it to work... help!

it worked for me with drupal 4.7, but now with 5.2 i can't get it to work.
i added <img> to the "filtered html" input format & checked "inline images"

the code it inserts looks like this:

test<span class="inline left"><a href="/?q=node/138"></a><span class="caption" style=""><strong>test: </strong>test</span></span>

there is nothing in between the link tag & no img tag:

test<span class="inline left"><a href="/?q=node/138"> ! nothing here ! </a><span class="caption" style=""><strong>test: </strong>test</span></span>

if i add something there, it will link to the image. so the image got created just somehow the code it inserts is messed up... how can i get this to work right?