It might help if you tell
- at what statement exactly this error occurs (use debug to find it)
- the text of the error message
- where the macro is located
- if the macro compiles without errors
- the version of MS Word you use

A few remarks:
- "workbook" is a term associated with MS Excel. Are you sure it's correct?
- what's the use of closing and reopening the document
- I don't like all those quotes arond the filename, one seems enough, three seems too much