PHP 5.1.6 issue with interface

[lupito]

I am getting following error with PHP 5.1.6:\[code\]Fatal error: Declaration of Tl1Telnet::ExecuteCommand() must be compatible with that of telnet::ExecuteCommand()\[/code\]ExecuteCommand is implemented correctly defined in interface.\[code\]interface telnet {public function DoTelnet();public function ExecuteCommand($command,$fh);}class Tl1Telnet implements telnet{public function ExecuteCommand($command,$fh = NULL){fputs($this->socketResource,$command);sleep(2);$tl1_string = fread($this->socketResource,30000);if($fh != NULL){fwrite( $fh, $tl1_string );}return $tl1_string;}}\[/code\]