SSAS Cube sales is not matching with fact table sales

Hi

I am new to SSAS I have an existing cube(which is not created by me) with Invoice sales and OTD sales, when I browse cube in BIDS it is showing huge difference than it is showing in fact table or view for Internal sales for OTD sales it showing right sales.

Here is an example

Dealer        OTD sales     Internal sales          Supposed to be

X               62724.83      1106366.035   ---> '63372.98'

When I queried internal sales fact table sales is '65372.98' which is close to OTD sales. 

I wonder why it is showing different amount in cube than fact table. Please advise!

Thanks!