I can only buy 1 item in my store. It gives an error when buying

I can only buy 1 item in my store. It gives an error when buying 2 or more items.

The error I get is as follows

"The amount sent must be equal to the total amount of all breakdowns"

How can I fix this error?

Hi, did you set the stock amount more then one at this article and also at the option?
Be sure that you did not place a point after 1 like 1.00

Have a great day!

Tonny

Ps check the max order quantity

The error is not fixed like this Payment Transfer Error: The amount sent must be equal to the total amount of all breakdowns

View code on GitHub