What version of EV is it you're running? Not sure if you've checked the below, but there are some points to note:
- Check the support matrix to see if you need to enable backup mode with the version of backup software you use. I used Veritas NetBackup 5 and 6 and all is OK
- When you restore placeholders to another server, you should rename this server to match the original name that the placeholders came from. You also need to keep the placeholders in the same directory as before otherwise they will not recall from the Vault Store
- With regards to the file size on disk, have you set the "FileSizeEmulation" within the Registry? It's found under HKLM->software->kvs->Enterprise Vault->FSA-Placeholder. Give it a value of '0' which shows the placeholders actual size as opposed to the size of the archived file.
Hope that helps...