the pin cannot start with 0. if you try it throws invalid pin. probably because whatever command php uses to determine the length cuts leading zeros.
bug just cost me a pool worker :-(

in register.php (onyl one i looked at) look for this section

 //valid date authpin is valid
                        if($authPin > 9999){
                                if(!is_int($authPin)){
                                        $validRegister = 0;
                                        $returnError .= " | Not a valid authpin";
                                }
                        }else{
                                $validRegister = 0;
                                $returnError .= " | Authorization pin number is not valid";
                        }

change the strlen($authpin) >=4 to what i put there so it looks just like that.

In lieu, another suggestion was strlen(('x' + $authpin) -1)