Mail Merge COM error

[countdrak]

I am trying to use mail merge using COM in Coldfusion MX. I keep getting this error.

An exception occurred when executing a Com method.  
The cause of this exception was that: AutomationException: 0x800a11fd - This method or property is not available because the document is [b]not a mail merge main document[/b]. in 'Microsoft Word'.  

58 :     /* Execute the mail merge */
59 :     /* This method returns a document object to the documents collection */
60 :     objMailMerge.Execute();

I think my word document is setup as a Mail Merge document. I have connected it to my SQL Server databse. And have the mail merge fields setup. I have checked it in Word and seems to work. How do I check if its actually a mail merge document?