The England international has failed to impress since the huge turmoil in his personal life.
“There is nothing to worry about with Wayne,” said Fletcher.
“Wayne is a top player and the goals will come because he has so much quality.
“It is up to us create the chances for him and give him the opportunities to score.
“Maybe we have not done that lately. Against Rangers we didn’t create anything for him.
“He will be frustrated with that but it will come.”