Hi, Marina! Jessica's right.
You must rename the file on your hard drive before you upload. When you scan or photograph your cards, your scanner or camera gives the file a default name.
I just peeked in your gallery, and your files are all named "card24" or something similar (different numbers). Chances are, you've uploaded that same file name before, even if it is a different card.
We approve all images, and then do a scan for duplicates several times a day. Comments can be posted, but once we scan to remove any duplicate file names, they are gone along with the upload. Our gallery software's not smart enough to realize your card24 and the next card24 are not the same card, and *poof* they go!
Let me know if you have any questions - I'm happy to help!
ps: this thread in site suggestions has some info that can help, too:
Forums at Splitcoaststampers