passing commands via ssh

Hello all, I am trying to execute a command on another server from my web application. I need to execute the command via ssh for security reasons. I have a private key/passphrase installed for ssh so that I can run ssh without a password. The command: ssh -i vertex vertex@wolf TX 77041 COD 10000.00 Works from my box's command line. The vertex 'key' for ssh is also in the same directory. But when I run system(ssh -i vertex vertex@wolf TX 77041 COD 10000.00) from my script I get an error: Host key verification failed. Also, when including the return status var I get different values such as: 255 or 127 or 1....But I do not know what these mean. This may not be a php issue but a webserver issue - sorry but I have no ideas at this point. Do I need to look in to some other functions to facilitate this? I did try passthru() and exec() with similar results. Any help is as always greatly appreciated. Thx Mignon