Error when creating a new mailbox.

When I try to create a new mailbox I get the following error. Forest1.net is my domain name. exuser is the name of the new user account.

Summary: 1 item(s). 0 succeeded, 1 failed.

Elapsed time: 00:00:01

exuser
Failed

Error:
Load balancing failed to find a valid mailbox database.

Exchange Management Shell command attempted:
New-Mailbox -Name 'exuser' -Alias 'exuser' -UserPrincipalName 'exuser@Forest1.net' -SamAccountName 'exuser' -FirstName 'ex' -Initials '' -LastName 'user' -Password 'System.Security.SecureString' -ResetPasswordOnNextLogon $false

Elapsed Time: 00:00:01

Thanks and Regards, Radhakrishnan