Permision denied after unprotecting Word document

Hi,
I have a strange problem.
I have an Outlook form which enables track revisions in Word document and protect it.
In another form I unprotect the document and then move it to another folder.
If I add revisions between the protect and unprotect everything goes fine, but if I don't touch the document after I do unprotect I get an error "permission denied" when trying to move the file.
what can I do?
here's my code:
1.
<VBCode>
Set myDoc = GetObject(spath)
myDoc.TrackRevisions = True
myDoc.Protect 0, True, myPass
myDoc.Save
Set myDoc = Nothing
</VBCode>
2.
<VBCode>
Set myDoc = GetObject(sourcepath)
myDoc.UnProtect myPass
myDoc.Save
Set myDoc = Nothing

</VBCode>
3.
<VBCode>
set fso = createobject("scripting.filesystemobject")
fso.MoveFile sourcepath, destpath
</VBCode>