How to write the trigger that works when I am deleting the data?

Question

Hai,

I have the following table,

Table1: tblTransaction

| SlNo | Date | ClientID | productID | Amount | Weight |

Table2: tblAccount

| ClientID | Name | Description | BalanceAmount | BalanceWeight |


the problem is when I issue a transaction it may have more than one product so in the same SlNo there are more than one rows in the table

The trigger I write like this,

-------------------------------------------------------------------

CREATE TRIGGER myDeleteTrigger on tblTransaction
AFTER Delete
AS
BEGIN
 Declare @SlNo as nvarchar(20),
 Declare @ClientID as nvarchar(20),
 Declare @Amount as decimal(18,2),
 Declare @Weight as decimal(18,3)

 set @SlNo = select SlNo from deleted
 set @Amount = select Amount from Deleted
 set @Weight = select Weight from deleted
 set @ClientID = select ClientID from deleted
 set @BalanceAmount = select BalanceAmount from tblAccount where ClientID = @ClientID
 set @BalanceWeight = select BalanceWeight from tblAccount where ClientID = @ClientID

 Update tblAccount set BalanceAmount = @BalanceAmount - @Amount where ClientID = @ClientID
 Update tblAccount set BalanceWeight = @BalanceWeight - @Weight where ClientID = @ClientID

--------------------------------------------------------------------

here the problem is since I have more than rows with the same SlNo, error occurs during this trigger works
so I think my problem is solved if I get the code to take sum of Weight Deleted

If any body know more about trigger and any other solution to solve my problem please help me

Thanks in Advance