Retrieving Windows user name and Computer name in Thin CLient

Using Thin Client I want to get the Windows users name and computer name from the client side, I am getting the user name and computer name from the server, I know I can get information using dll's such as Kernel GDI32 this particular dll is ADVAPI32.DLL and then I am calling GetUserNameA,  GetComputerNameA this works just file if the connection is a mapped drive to the server. I used one of the sample programs GETUSERNAMEANDOS.cbl to get the logic and into one of our standard programs. I have been able to get the other information from the kernel.dll in thin client but not the ADVAPI32.DLL, any ideas?