Error in Formula Processing when Entering SO Line

Hi All,

1- I am trying to enter a Sales Order.

    SO header information is entered.

2- When SO Line is Entered and when clicked on "Book Order" , I am  getting below error :

  Error in Formula Processing

  Formula : Handling

Step No: 1

This pricing attribute ( with Context Pricing Attribute and Attribute - Handling Cost ) has NULL values

3- After entering  ,Pricing Context and Handling Cost , The Unit Selling Price gets disappeared and when try to manually enter the unit selling prices , I am getting below error:

  "Online discounting is not allowed: Zero or No list price "

Thanks,

Regards,

Yogesh