Update PHP from 5.3.29 -> 5.5

[fons]

Hello,

I'm new here and can't find how I can update my PHP from 5.3.29 -> 5.5
I've tried

cd /usr/local/directadmin/custombuild
./build update
./build clean
./build php n

Now my PHPO version is 5.3.29


Thanks
Fons