Problem Creating Mailbox


After creating the user in AD (with user principal name) by using the Create User activity available inside the ActiveDirectoryDomainService Package successfully, the Create Mailbox (Exchange Server) activity throws error -

Create Mailbox: An unexpected error has occurred: System.Management.Automation.RemoteException: The operation couldn't be performed because object '' couldn't be found on ''."

If I try after some time like 10 minutes then it doesn’t throw any error.

What could be the reason of the problem?
What is the workaround?