Errors with chan_zap.c when installing asterisk-1.2.0-rc2

Hi

I am trying to install Asterisk-1.2.0-rc2 on Ubuntu Linux and am getting a lot of errors with chan_zap.c. Most of the errors look like this:

Chan_zap.c:10927: error: dereferencing pointer to incomplete type

I have already successfully installed the same version of Zaptel. Any ideas what the problem could be?

Thanks

langals