some problems with chpst again

Hi,
For past few days I am trying to get clamd working with runit and ipsvd,
but have problems.
With softlimit, it runs fine. My run file was,
#!/bin/sh
exec 2>&1
exec  softlimit -a 40000000 \
    /usr/local/sbin/clamd

But with chpst it has problems,
#!/bin/sh
exec 2>&1
exec /usr/local/bin/chpst -m 40000000 /usr/local/sbin/clamd

I get error in /tmp/clamd.log as,
Tue May 11 08:55:43 2004 -> ERROR: pthread_create failed

What must be wrong? Once I comment the chpst line and put softlimit
line, it works again.

Thanks a lot in advance.
With warm regards,
-Payal