Stroed Procedure Problem

I am having a problem with the following SQL code. It will be a stored proc once it works.

I have a variable @CardNumber. The last line of the SELECT Statements says: Where Card.CardNumber=1234/*@cardNumber*/

The Query works when I have the number hard coded on this line. It does not work when I try to use the variable by uncommenting it and removing the 1234.

Please help. This has to be simple!

Thanks!!!

- Mike

Declare @Balance money
Declare @Fee money
Declare @CustomerNumber int
Declare @TransAmount MONEY
Declare @TransType Int
Declare @CardNumber int

SELECT DISTINCT
@TransAmount=100,
@CardNumber=1234,
@Balance=1000,/*Card.CustomerBalance,*/
@CustomerNumber=Card.CustomerNumber
From dbo.Card Card
Where Card.CardNumber=1234/*@cardNumber*/

Select
@Fee=1.50/*SC.ATMWithdrawalFee*/
From dbo.ServiceCharge SC
Where SC.CustomerNumber=@CustomerNumber

If @Balance > @TransAmount + @Fee /*@transamount*/ /* MAKE SURE THAT THEY HAVE*/
/* ENOUGH MONEY INCLUDING FEE*/
Update Card
Set CustomerBalance=(@Balance - @TransAmount - @Fee)
Where Card.CardNumber=1234