NAT-PT under uClinux

When we implement NAT-PT under Linux 2.4.20.

Everything seems ok!

BUT! When we want to port it on uClinux 2.4.20 with MIPS compiler.

It has something wrong with following messages:

../nat-pt: initialise_packet_filter: Error setting IPv4 device packet
filter: Invalid argument

....and does not work anymore

We guess, it might happen at "setsockopt(*pDesc, SOL_SOCKET,
SO_ATTACH_FILTER, pFilter, sizeof(*pFilter));"

What are we missing?

Any hint/comment apperciated.