[Zope] python with thread

I've installed python1.5.2 on a HP-UX unix box for me everything is running well but when I try to install zope2.1.6 I have an error in /usr/local/Zope-2.1.6-src I run this command : python1.5.2 w_pcgi.py but it returns me this error Building the PCGI wrapper: Error : Zope requires Python thread support! can you help me to run Python with thread on HP-UX 10.20 unix box ? thanks in advance LR