Wheat beer starter did not work

[beer gut]

Hi All I am having a issue with my Wheat beer starter. I done my normal starter 300ml water to 55g spray malt boiled for 15 mins the it is cooled then I pitch in the liquid yeast. Now I have never done a wheat beer yeast before so I don't know if they are slower than the English Strains but this bottle has been going for 2 days now at 20oc and they is little to no action, normally by now I have a thick top and it's ready to pitch. They is a good amount of yeast at the bottom of the bottle it just seems to be dead. So are Wheat beer yeasts slower than other strains or is this one dead and has to be chucked out?