Excel Add In does not work

Hello,

we have ALM 11.50.444 installed and it generally works fine.

I have installed the Excel Add In on my WIn7 64bit OS with Excel 2010 32bit and parallel Office 2013 (without Excel installed).  When I run the Excel Add in it always produces an error in step 2 (after having confirmed the server URL) - the 

error msg. reads: "A general error has occured: The required ALM client files have not been downloaded....."

The installation of the Add In had been completed without errors.

Any hints or clues?

Thanks in advance,

Ovid99