Yes - we have a C# application making calls to RPG programs - make sure you are generating the Interface c# interface parameters
{
obrun = getCallMgr().getObRunnable(fnc, getObVariableGroupX("LOAIRISConnect.FNQWLXWR_ObIn"), getObVariableGroupX("LOAIRISConnect.FNQWLXWR_ObOut"), "LOAIRISConnect.FNQWLXWR_ObFnc", "API", "RPG400", "" );
if(obrun != null)
Build a code library and include all the RPG programs that you call and it will include the interface defenition