Asterisk a2billing in Ubuntu Linux

After trying many times I was able to install Asterisk 1.4.1 on Ubuntu, then I tryed to install asterisk2billing, when I make the call on the console of Asterisk you can see that the billing script start but it stop at certain stage, I don’t knw why I installed all the libraries needed, I was able to installe it on suse linux after doing this

      cd /usr/bin
 ln php5 php

in suse the link to php was not found, but doing the same for ubuntu do not solve the problem, I am sure its system problem, but I don't know what