Sync Bo Level

Hi

I am not sure about the Data retrieval levels in Sync Bo.

I have a scenario where I need to read data from 4 tables or 4 levels of data(Inner Join). I have build a GETDETAIL function module for the same and used in only one SyncBo, but no data is being retrieved.

Does that mean I need to build separate SyncBo for each level and then relate every SyncBo with each other.

Can't we retrieve data from four different levels in one Sync Bo and also is there any restriction on the level of interrelated Sync Bo's we can have.