How to correctly run 'rename-item' remotely?

Question

I have declared the following variables:

$dir = 'C:\Users\user1\folder1'
$fname = 'abc.txt'
$tmp_fname = 'abc1.txt'

Now, I am remotely trying to execute below command:

invoke-command -cn $mycomp -Credential $mycred -ScriptBlock {
param($fname, $tmp_fname)   
   rename-item $dir\$fname -NewName $dir\$tmp_fname
} -ArgumentList ($fname, $tmp_fname)

Upon executing the above command, I am getting below error:

+     invoke-command -cn $server -Credential $host_cred -ScriptBlock {
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [Rename-Item], PSInvalidOperationException
    + FullyQualifiedErrorId : InvalidOperation,Microsoft.PowerShell.Commands.RenameItemCommand