Hi, you need to have your variable mapped like below:
So the CustomProperty block mapping must include slddrw, sldprt, sldasm, then add a $PRPSHEET block with slddrw as the file extension.
Then when you create a part and fill in a Description property and save it into the vault. Then create a drawing, and save it into the vault, the property from the part will be copied over to the drawing. NOTE - for this to work, you MUST have the SOLIDWORKS PDM add-in active:
Hope this helps.
I was missing the $PRPSheet on the variable...the same time i saw your post I found it in the help.