Calculation Schema for Services

Dear Experts,

We are looking for incorporating the Calaculation Schema for Service Line items. In the standard Scehma MS0000, I am unable to add the account key. Please let's know the configuration of account keys for Service Schema. Account Keys / Transaction Even Keys defined in Purchasing - Conditions are not avaialble for selection here.

Request for inputs in implementation of Calculation schema for Services please

Regards,

Ramakrishna