The code must reside in the ThisWorkbook module. It won't work if it
resides in any other module. Also, the name of the procedure is
"Workbook_Open", not "Open_". And, of course, it won't work in VBA
procedures are disabled.
Cordially,
Chip Pearson
Microsoft Most Valuable Professional
Excel Product Group, 1998 - 2009
Pearson Software Consulting, LLC www.cpearson.com
(email on web site)