Error: lrdo_iniatialize_db. "OCIInitialize"

I am running LR 11.52 controller with several Load Generators executing Oracle tier 2 and Web services protocols, on 2 of the involved Load Generators, Ms Win 7 64 bit i am getting the following:

Error: lrdo_iniatialize_db. "OCIInitialize" return code = XXXXXXXX

any idea how to fix this?