Customized Discount error in Commerce SDK

[Tech-Kishan]

Other Development Issue

Summary

Describe the issue
We have a customization of employee/customer Discount with affiliation. we limit the discount to 1500 for employee/customer for a month. If employee/customer has used all of the given discount then we don't give any more discount. But the problem we are facing right now is when a employee/customer had used all the discount and if a user gives him manual discount then the discount applied is shown zero on line level but on discount screen of total it shows value which is not right. So how can we solve this issue. I have provided the code screen shot where the condition being applied as well as the result.
Version and Error Info
Commerce SDK Version: 9.44
Exception/Error Details:

Screenshots

Here is the Code that get to the result of what we are doing

And Here is the result with error