No ring tone when using G.729 via pass-thru

I am using G.729 pass-thru calls on my Asterisk. The problem is: no ring tone can be heard at all. I tested with G.711 and everything had worked just fine.

Anyone has an idea of what´s wrong ?!

Thanks in advance.

try disabling progress inband in sip.conf?

It didn´t work. Any other suggestions ?!

Thanks

post the dialplan?