Have you got any settings for your shader?
Like;
Settings = {}
Settings.var = {}
Settings.var.bloom = 1.5
Settings.var.blendR = 355
Settings.var.blendG = 355
Settings.var.blendB = 355
Settings.var.blendA = 100
I forgot who the author is buh yea, add this to your code replacing line 8:
local col = tocolor(Settings.var.blendR, Settings.var.blendG, Settings.var.blendB, Settings.var.blendA)
dxDrawImage( 0, 0, screenWidth, screenHeight, myShader, 0,0,0, col)