key error while producing events

Hi

 I am trying to produce some events in gluon gluon fusion process by changing the PDF to cteq5l1.
I could produce the events in vector boson fusion process using cteq5l1 but in ggf, I am getting some key error. I ran the following commands

generate g g > h h [QCD]
output test
launch -m
set pdlabel cteq5l1

& I got the following error
INFO: Combining Events
Command "generate_events run_01 --nb_core=2" interrupted with error:
KeyError : 'cteq5l1'
Please report this bug on https://bugs.launchpad.net/madgraph5

Please help me to solve this problem.

Thanks,
Saswati