Creating Expense Allocation Schedule

Hi,
    I am trying to test the feature of 'Expense Allocation Schedule'. Based on the NetSuite documentation, i am trying to allocate expense from one account into two other expense accounts. I get following error message when i try to create Journal Entry:
'The Allocation sources or destinations did not have any expenses associated with them for the selected period.'

(Note:- The source and destination account do have some balance in them)

I am not able to understand what exactly should i do to successfully allocate expenses and create Journal entries.
I discussed this problem with NetSuite Support person and according to him, i should create Line entries for each department asssociated with the Source Account. We have total 45 departments and I don't think we have create 45 line items with one source account say 'Allocated Expenses - Facilities-In' and 45 different departments.