Cannot install MS Word plugin to office professional plus 2010

I have Mendeley installed and want to use citation in word 2010. When I clicked on "Install MS Word plugin" in tools, the software reports that Mendeley cannot find microsoft word, I may have a "click-to-run" version of microsoft office. However, after a while of working around I understand that the "click-to-run" versions of MS Office are restricted to office starter and office Home and Student. Since I have the Microsoft Office Professional Plus 2010 installed, I don't think this is the problem. Can anybody help out with this? Thank you very much!