Thank you for your post.
What version of FileMaker Pro are you using?
There are some issues with FileMaker Pro accessing the 64-bit version of Outlook.
Any other information you can provide may be helpful in narrowing down the possible causes.
I am having the same problem on multiple client computers (government)
- Filemaker 13.0v5
- Windows 7
- Service pack 1
- Outlook v14.0.17153.5000
- Office Professional Plus 2010
Sounds like an issue previously reported and acknowledged.
For More Information see: FileMaker 14 64 Bit and Send Mail via Email Client Outlook 64 Bit Not Working
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip