There must be some errors in the output while php is compiled. Please post these errors here.
After that, the directory where I unpacked the ispconfig tarball is gone (I copied the tarball in /root/ispconfig then /root/ispconfig is deleted with it's content)
I tried removing the commands that remove the directories in compile_aps/compile and found that the php binary that ispconfig's installation tries to use later on is symlinked to nowhere, and thus it fails in the line showed above.
The install_ispconfig direcorie must be deleted. If you run the setup twice without deleting the directory, it will fail!