I’m trying to encrypt a file at rest with EFS remotely with WinRM.
I wrote the following code in Powershell:

$username = "DomainUsername"
$password = ConvertTo-SecureString "Password" -AsPlainText -Force
$credential = New-Object System.Management.Automation.PSCredential($username, $password)
Invoke-Command -ComputerName RemoteMachineName -Credential $credential -ScriptBlock {
    $filePath = "C:PathToFile.txt"
    $file = Get-Item $filePath
    $file.Encrypt()
}

But I get the following error:

Exception calling "Encrypt" with "0" argument(s): "Access to the path 'C:PathToFile.txt' is denied."
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : UnauthorizedAccessException
+ PSComputerName : RemoteMachineName

I checked the user context with:

Invoke-Command -ComputerName RemoteMachineName -Credential $credential -ScriptBlock {
    whoami
}

and it returns the DomainUsername

I run directly on the targeted machine

$filePath = "C:PathToFile.txt"
$file = Get-Item $filePath
$file.Encrypt()

and it encrypts the file correctly.

What can cause the exception?