Discount problem in marketing document

Dear All,

I have one problem. In sales quotation while posting our discount % is zero.

But after posting if user updates the unit price for item in the quotation automatically the discount % displays 100% and makes document total zero and we get the following.

[Sales Quotation - Rows - Discount % per Row][line: 1] , 'You are not permitted to perform this action' [Message 200-30]

If we edit the discount to zero then it allows to update the document.

Any solution for this. Also i dont want to use discount in quotation.

swapnil