php check entry problem

[nokmaster]

hello, can anyone help me with check entry and insert if not in my database..

my code is:

if ($Worked) {
    echo "Credit=$Credit";

if($Credit=="0"){

//Update account
$Result = mysql_query("UPDATE tblUser SET Credit='0' WHERE Username='$Username'and Password='$Password'") or die ("");

} else {

//Check IMEI
$Result = MYSQL_QUERY("SELECT * from tblAsk WHERE sIMEI='$IMEI'") or die ("");

$Worked = mysql_fetch_array($Result);

$IMEI = $Worked[sIMEI];

if ($Worked) {
    echo "SERVER: ASK file is already in queue ...</br>";
    echo "SERVER: DCT4, request queued in 30 sec upto 48 hours.</br>";
    echo "SERVER: Relogin to check your request status, resend ASK to get your RPL.";
} else {

$Credit -= 1; //Decrease by 1

//Update account
$Result = mysql_query("UPDATE tblUser SET Credit=$Credit WHERE Username='$Username'and Password='$Password'") or die ("");

//Insert to tblAsk
$Result = mysql_query("INSERT INTO tblAsk (Username, sIMEI, sCHANGED, sASIC, sDATA) 
VALUES ('$Username', '$IMEI', '$CHANGED', '$ASIC', '$DATA')");

}

}

} else {

    echo "SERVER: Invalid username or password, please check your details and try again !";

}
mysql_close($con); 

when i tried inserting IMEI in my database it insert but BLANK, what im trying to do insert and IMEI into my database and if its already there then do not INSERT.

what should i do?

Thanks!

Regards,