PushDialog: Invalid Control

In my main.cs file, I have the following gui files being executed...

// Execute gui files.
   exec("~/gui/mainScreen.gui");

   exec("~/gui/RLMMainMenu800x600.gui");
   exec("~/gui/RLMQuitWindow800x600.gui");

   exec("~/gui/RLMTeamSelectNRL800x600.gui");
   exec("~/gui/RLMDrawGenerationNRL800x600.gui");

   exec("~/gui/RLMMainBuilding800x600.gui");

   exec("~/gui/RLMManagerOffice800x600.gui");
   exec("~/gui/RLMLeagueTable800x600.gui");
   exec("~/gui/RLMTeamStatistics800x600.gui");

   exec("~/gui/RLMCEOOffice800x600.gui");

   exec("~/gui/RLMTrainingRoom800x600.gui");
   exec("~/gui/RLMTeamLineup800x600.gui");

   exec("~/gui/RLMMedicalTreatmentRoom800x600.gui");

   exec("~/gui/RLMBankManagerOffice800x600.gui");

   exec("~/gui/RLMMatchDay800x600.gui");
   exec("~/gui/RLMMatchOver800x600.gui");
   exec("~/gui/RLMPostMatchPoints800x600.gui");
   exec("~/gui/RLMPostMatchStatistics800x600.gui");
   exec("~/gui/RLMInterview800x600.gui");

   // Exec game scripts.
   exec("./gameScripts/game.cs");

But when the command on one of my buttons is "canvas.pushDialog(RLMMainBuilding800x600);", it returns a "pushDialog: Invalid Control: RLMMainBuilding800x600". The thing is, it used to load it fine, but now that gui doesn't turn up in the gui editor, either, even though all of the other guis in that list do. And the actual .gui file is still in the gui folder. Any ideas?