Stock Quantity Message to Block orders

[ABC]

I am using this program for a auto parts shop.
I started using your program but I notice that it is giving me some problems.

If a product quantiy is at zero and I try to add the product to the order window, the program will give me a message blocking the product.... This is fine .

However, If the product quantity is at 1 or any number, you can add and cash out any amount of that product. Now this is bad for my type of business. This means I am going to cash out what I dont have in stock. Which is going to turn off my customer and waste their time and ours.

I am thinking there is some issue in regards to calculation in the program, but please let me know what the issue is.

I would like the program to be able to calculate what I am ordering against what I have in stock and add it if I have that amount and block me if what I am ordering is over the amount in stock.

Please help me with this issue.

I have seen questions similar to this but not the exact issue and there was no resolution which would suit my specific issue.

[JamesBotch]

Have you found out the solution? I'm having the same issue as well.
Cheers,