[asterisk-users] asterisk 11 and no RTP

[Jerry Geis]

>   Error loading module 'res_rtp_asterisk.so': /usr/lib64/libavformat.so.52: undefined symbol: av_tree_node_size
This is the error I get when trying to start Asterisk 11 on centos 5.

Asterisk 11 works fine on my centos 6 box - I also verified that on centos 6
I do not have the above mentioend file.

ls /usr/lib64/libav*
libavahi-client.so.3      libavahi-common.so.3      
libavahi-core.so.6        libavahi-glib.so.1        
libavahi-ui.so.0          libavc1394.so.0
libavahi-client.so.3.2.5  libavahi-common.so.3.5.1  
libavahi-core.so.6.0.1    libavahi-glib.so.1.0.1    
libavahi-ui.so.0.1.1      libavc1394.so.0.3.0

Is there another library it can use "instead" of libavformat? something 
I have installed on Centos 6
and not on centos 5?

Thanks

Jerry