How to invoice fixed price per service orders

[taoudia]

Dear gurus,

My company is providing electrical maintenance services and we'd like to used the CS module. Below is the basic business flow I want to implement:

Creation of the service order (IW31)

Selection of the service performed among a list (Service Product?)

Perform the job
Request for billing DP90 (only the selected services should be retrieved), the pricing will be done through the standard process (pricing determination in SD), one fixe rate per service product.

How should i set up my DIP Profile in order to retrieve these service products (i saw on the internet i have to check "Products" are relevant in ODP1, but it's still not working)?

Is it possible in that process to manage several service products for on service order?

Thanks in advance for your help