Trouble Trying to Hide Email From Address List Using PowerShell - powershell

Question

I am trying to run a simple command to hide an email account from the address list using PowerShell. Here is my code so far.
cls
$EmployeeEmail = "user#example.com"
#Need to hide the Mailbox from address list
$MethodName = "Hide Email Account"
$username = "staff"
$password = "accounts"
$secstr = New-Object -TypeName System.Security.SecureString
$password.ToCharArray() | ForEach-Object {$secstr.AppendChar($_)}
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $secstr
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri http://Exchmbca1.example.local/PowerShell/ -Authentication Kerberos -Credential $cred
Import-PSSession $Session
Set-Mailbox -Identity $EmployeeEmail -HiddenFromAddressListsEnabled $true
Remove-PSSession $Session
However, when I run this command I receive the following error message:
The operation couldn't be performed because object 'user#example.com' couldn't be found on 'servername.example'.
I have tried changing the value of the -Identity I pass to the Set-Mailbox cmdlet with 'DOMAIN\username' as well and I receive the same error. I know the account exists because I can do a search using Get-ADUser and find the account with the SAMAccountName. Any help would be much appreciated. Thanks!