An issue with using SCOPE_VARFETCH inside the IDL Workbench (discussed in this comp.lang.idl-pvwave thread) has been fixed in the IDL 7.1.2 patch:

The fix is CR56369 and it is now available in the IDL 7.1.2 patch release. Please note, you will need to contact ITT VIS Technical Support (TechSupport at ittvis dot com) for the link to download this patch. Be sure to mention your OS platform and architecture (32 or 64 bit). Other than this CR, this patch release fixes an issue with extended ascii characters.

Bill Okubo, IDL Product Manager