Adding another dice to the damage at lLVs 5,11 and 17?

I am making a cantrip for wizard and was wondering how i could go about adding another 1d4 bludgeoning and 1d8 cold respectively 

i already have the 1d8 and 1d4 damage working just can't figure out how to add more when the character hits those levels

This spell’s damage increases by 1d4 bludgeoning damage + 1d8 cold damage when you reach 5th level (2d4 + 2d8), 11th level (3d4 + 3d8), and 17th level (4d4 + 4d8).

ok nm i just needed to remove the spell and put it back to see the changes, its silly but it works