Little Richard's line was:

"You keep a-knockin' but you can't come in,
Come back tomorrow night and try it again"

though that wasn't the title as I recall. Maybe the actual title was Keep A-Knocking (just my guess). As for Smiley Lewis' "I Hear You Knocking", that was covered around 1971 by Dave Edmunds.

Talking of knocking, how 'bout "Don't Knock the Rock" - remember the old Bill Haley movie? Little Richard was in that, too.