Can't convert old mathcad file to mathcad prime 7.

I tried to convert old mathcad file but an error pops up ( I have a Mathcad prime 7 installed)

I also have enabeled the .Net Framewor....on my windows, but I still have the same error after that as well. I really nedd the files for my PhD project. Can someone help me with converting the old mathcad file to mathcad prime 7 file?

Thank you 

Tadele