MapVirtualPath in WCF service

Hi ,

I have created a WCF service (Powerbuilder 12.5.1.) and I have added some code that worked fine  in a classic asmx service

#IF defined PBDOTNET THEN

          ls_sourcefile = MapVirtualPath(ls_path)

          ll_pos = Pos(lower(ls_sourcefile), "\session\__webservice__\c")

          IF ll_pos > 0 THEN

          ls_targetfile = Replace(ls_sourcefile, ll_pos, 25, "")

          ls_sourcefile = ls_sourcefile + "\" + filename

          ls_targetfile = ls_path +  filename

          System.IO.File.Move(ls_sourcefile , ls_targetfile)

END IF

#END IF

The above code was working in a classic asmx web service.

Now that I'm moving in Powerbuilder .NET wcf service , I'm getting  the below error

Cannot find the element "MapVirtualPath".

I have added as a reference the mscorlib.dll (.Net framework 4.0) but still getting the same error.

Any ideas ???

Appreciate any help you could give me.

thank you