It's important to clear the colon first with a water enema before a coffee enema, or to do it after a bowel movement, otherwise you won't be able to retain the coffee solution.
You put 1 cup of the coffee solution in the enema bag, which means you just used 0.5 Tablespoon of coffee for the enema. This is far too weak in my opinion.
coffee enemas can be difficult to retain at first because of their effect on the peristaltic action of the intestines.