Alrighty, by 'not working', do you mean it isn't appearing in Cape?
-If it's this, make sure you did have the "Has portal" box checked off in your Map Maker. If it is, try re-exporting.
OR,
Is it crashing when you enter?
-If it's this, try turning down your View Distance, turn off water reflection, and switch rendering systems in-game, all of which can be found in Options, in the video tab. Lag could be the culprit in this case.