My service disccount problem

My service disccount problem

Hi Everyone i hope you are all fine i have1 problem my service is not active to the discount becasue i see this message every time in my service 

There are errors preventing you from submitting this service. Please cycle through the tabs and correct any issues highlighted in red.

Invalid Sale Amount - Sale amount must be more than 0 and less than the original service price
please tell me how can fix it!
Thank you