Struggling QPR are without a win in six matches after a 0-0 draw at home to Stoke.
Rangers have won just one of their past nine games – a run which has included five defeats and resulted in them sliding towards the Sky Bet Championship relegation zone.
They struggled to create clear-cut chances against injury-hit Stoke, who defended well and were mostly comfortable.
Chair delivered the ball in low towards the Scotland striker, who was unable to score from four yards.
At first it seemed that Dykes was guilty of an inexplicable miss.
However, an all-important touch from Stoke defender Nathan Collins slightly altered the course of the ball before it reached Dykes, causing him to slice wide of the target.
Chair was the stand-out player in the first half, sending one shot over and another wide as the home side threatened.
It was a totally different story after the interval, with Stoke putting Rangers under sustained pressure and almost going ahead.
Keeper Dieng showed superb reflexes to keep out Tymon's shot and the ball then ricocheted off Rangers defender Todd Kane and onto the crossbar.
Dieng was called into action again late on, diving to his right to keep out a low shot from Potters substitute Jordan Thompson.
Rangers' season has been blighted by a tendency to miss chances and then concede goals after a defensive lapse.
A clean sheet and a point after two successive home defeats will be some consolation for boss Mark Warburton.
But it was another frustrating game for the west London side, who lack a cutting edge up front.
Dykes has established himself as Scotland's number nine but has yet to reproduce his international form for his club, scoring just one goal in open play since his summer move from Livingston.
Rangers' wastefulness was summed up in stoppage time when Chris Willock blasted wide after more good work by the always lively Chair, who sent a wayward effort well over the bar in the final seconds.