Need Help with DataBase Programming in VB !

HI
my name is Sunny Guha and I am going to attend COFAS 2007. My project is to create an online shopping cart.

I'm getting a problem that I can't add all the entries of 1 field ie Cost. Plz help me . If possible attach a sample file.

Database in use -- access
prg - VB6

-Sunny Guha