Javi,
Thank you for your answering my question. I changed the code in scripts\customlib_extras\customlib_extras.tcl as you suggested. It worked ok after restarting GiD. Again, thanks for you help!!!
Attached are the example and problemtypes used for the test. (I just wanted to share this for others as future reference.)
wFAST2.gid.zip (171 KB)
test.gid.zip (34.8 KB)