Why can't my script find the GUI with filtering enabled?

Hi guys,

I have a module script that modifies the GUI of users when they finish a round of the game.

value.PlayerGui.MainGUI.Lives.Visible = false

is the line that causes the problem. The error is that "MainGUI" is not a valid member of PlayerGui. It certainly is and works without FE. I thought that server scripts could still communicate with clients even with FE, but clients couldn't communicate with the server.

Thanks, MD