Help. Install problem on FedoraCore 4

[xakmak]

Hi everyone! I try to install ISPConfig last stable on FC4 , installed Postfix, apache, mysql, etc... but it shows error during install-

1) standard
2) expert
Your Choice: 2

########## MAIL SERVER ##########

Checking for MTA...
./setup2: line 427: which: command not found
./setup2: line 427: which: command not found
ERROR: Your system configuration is not compatible with ISPConfig! The installation routine stops here!


Where i was wrong ?
Postfix (MTA) already instaled and running...
I dont know what to do... Please help.

[till]

Please install the program "which" from fedora 4. Did you follow one of the perfect setup howtos?