Help with TRex Installation

Hi, I am trying to install TRex (6.1.09.00) on my local portal (Netweaver 04 (640) - Stack 12) and during the 2nd last step of the installation I get the following message:

"error starting web server" and then the installation fails. When I checked the log, I got the following error message:

"The system cannot find the file specified.)in execution of a 'CreateProcess' function, line (278), with parameter (C:\usr\sap\Python
python.exe C:\usr\sap\trex_02/CCMS/install_config.py)".

I tried installing a couple of times and I always got the same error messages. Can anyone please help me? Thanks a lot for your valuable time.

Sincerely,

Sri