I am having difficulties about Multi-User Table Update.

There are 5 computers networked together and they run the same application which is developed using VFP5.
The problem is sometimes an update is not recorded in the currency table but the transaction is recorded properly in the transaction table.

Currency Table Data:

Field: curr1 Balance1
USD 90,000
SGD 170,000
YEN 35,000
.
.
etc.

Five computers run at the same time to serve the customers who want to buy or sell their Foreign Exchange Bank Note. This program uses a simple formula to update field Balance1 with Addition or Subtraction.

If a customer sells SGD 800 then SGD currency in the Currency Table will be added by 800 and the Balance1 becomes 170,800.
If a customer buys USD 2,000 then USD in the Currency Table will be subtracted by 2,000 and the Balance1 becomes 88,000.

The problem is sometimes the addition or subtraction process NOT RECORDED in the Currency Table but the Sale / Purchase transaction is recorded.

Thanks a lot for your kind help,
Regards,