How do you initialize this driver? If you are using VI_FALSE for IDQuery, driver does not check instrument type and using default model hpe3631a.
a) Enable id query in your init function
or
b) specify DriverSetup in option string of hpe3631a_InitWithOptions.
hpe3631a_InitWithOptions(vi, "GPIB::14::INSTR", VI_FLASE, VI_FALSE, "DriverSetup=Model:E3634A", &vi);
More information you can find in help of option string parameter. (function hpe363xa_InitWithOptions).
If you are using Class driver, you can specify Driver Setup in Max too.
Zdenek