ISA and PIX BAck-to-back dmz

[cceng]

I am trying to put together a back-toback dmz with private addresses in the dmz. I can ping from the internal network through the ISA box to the internal interface on the pix in the dmz, but I can't get out to the outside world (any protocol).

I have a system in the dmz between the pix and ISA box. That system can ping out through the pix to the outside world. So it doesn't look like a configuration issue on the pix.

Any ideas on what I am missing here?? Does it have to do with double nat'ing?

Thanks!