No 'Create Activities' dialog box appears at end of email mail merge on list members?

Dear All,

(Sorry for my English)

One of my clients experiencing a strange issue. When they use mail merge, the Create Activities dialog do not appear. We use CRM 2011 update roll up 13 on the server an in the client we use update roll up 10. The other computer that use roll up 10 works, only one computer experiencing this issue.

I hope someone could help me with this issue Thank You