The gpib-32.dll is found in C:\windows\system\gpib-32.dll.  This error actually occurred because the dll was not found in the path given.
However, the regsvr32 utility will only work for ActiveX dll's.  Thus, the attached error will occur.  The gpib-32.dll is not an ActiveX dll, but it is possible to write an ActiveX wrapper for the dll.  Consult other web resources on how this is done.
Randy Solomonson