ESS: Travel Management Cross Company Cost Assignment

Question

Hi All,
We have one scenario in (ESS) Travel Management.
While raising travel request, employee is having the option of selecting Cost Assignment
where in employee selects WBS Element and Cost Center.
Here in we have two company codes
1. 1000
2. 999
Now employee belonging to company code 1000 should have option to select WBS of company code 999.
Currently system is throwing error
The CO account assignment object belongs to company code 999, not 1000
Now if we change this error message to warning message it will impact on all other
applications running in R/3.
This requirement is only limited to Travel Management.
This application uses following webdynpro application,
FITV_VC_COST_ASSIGNMENT
Please provide the appropriate solution either technical or functional.

Answer 1

System will follow the strict rules while posting transactions to cost objects by the employees.
The user is authorized to post only in 1000 but not in 999. so he can't post to 999.
People with authorization to post to 999 can do it.
But the main thing is, Cost centers are belongs to only one company code so U can't post this transaction to 999. 
The transaction which u r trying is seems to be cross company code transaction.  Cost objects should relate to the company code where U r posting transaction otherwise u cont post it.
IF possible provide more details.....