Powershell – Enable and disable scheduled task with PowerShell and variable

if I try to enable and disable a scheduled task with PowerShell this works.

Enable-ScheduledTask -TaskName "Name of my task"
Disable-ScheduledTask -TaskName "Name of my task"

But if I'm trying this with a variable I'll got an error.

$TaskName = "Name of my task"

Enable-ScheduledTask -TaskName "${TaskName}"
Disable-ScheduledTask -TaskName "${TaskName}"

How could I do this with the variable?

Edit:

This error occurs.

Enable-ScheduledTask : Das System kann die angegebene Datei nicht finden. (The system could not found the file)
+ Enable-ScheduledTask -TaskName "${TaskName}"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (PS_ScheduledTask:Root/Microsoft/...S_ScheduledTask) [Enable-ScheduledTask], CimException
    + FullyQualifiedErrorId : HRESULT 0x80070002,Enable-ScheduledTask