Why VS2010 MFC program with NI driver can't work in other PC

Hello,

     I have installed NI MAX software on my PC. I create a 32bit MFC program using VS2010, the program will call NI Driver(visa32.dll and NiViSv32.dll), I put these 2 *.dll in my exe program's folder. I can access instruments(Keithley Power supply, Fluke8816A meter and etc.) using VISA interface, it works without any problem. When I send the this program to my colleague, he can't use this program to access instrument. Even the program can't set the instrument from local to remote in his PC. He has also installed NI MAX software. I add some debug message and only "cannot open a session to the device" message was print out. What's the possible reason for that? Thanks.