Hi sidhi705,
ebay made a change a few months back to require the Header and Gallery photo be the same at submission, which affected the Auctiva one-page lister's ability to provide two separate photos, one for Gallery and one for Header.
I saw one of the Auctiva folks recently post that they are aware of the problem and were going to remove that feature from the one-page lister in a future release. That problem has caused alot of members to report a similar problem of incorrect Gallery photo. If that's what you are doing, it's the cause.
As for fixing an active auction(s), I'd try using the ebay Revise listing and delete and re-add the Header picture (that's the free one) directly to ebay or change its URL link back to Auctiva to the correct picture. If that doesn't eventually replace the Gallery picture, I have a fix for that too.
Danno