Arcserve 11.5 - applied SP4 and now get media errors

HELP!!

I updated to SP4 HOPING to resolve some tape usage errors in said product and now I get "unable to position media" errors, no backups are being done.

Arcserve 11.5 on Server 2003 SP2.

I assume that araczec has already solved this one out. But remember not only to upgrade the SP's also keep in mind that Device Patches are also needed.
regards
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Best regards,
Carlos Alberto