Whenever you are writing a powershell module, in .Net say, and testing it from another script in ISE, it’s good practice to remove the last version of the module from a session before loading the new version into memory.
Get-Module MyLovelyHorse | Remove-Module
Import-Module MyLovelyHorse -ErrorAction Stop
This snippet finds the module if it exists in the current session and removes it before re-importing (the new version of) it. If you don’t do this or start a new session, the original will stay around in memory and any changes you think you are making won’t show up when you run the test script.