FLASH POWDER HELP ASAP?

i have 425 mesh aluminum powder. when i mix it 1:1 KNo3 it literally does nothing. i used a fuse to light it and it wont even light and if it does its super slow. My KNo3 is from stump remover and my al powder i got on ebay. the al powder is very very fine so i doubt thats the problem. Can anyone help ASAP. also i am working in a safe area and using protective gear and wearing glasses but at this point it doesnt even seem like i need them because this isnt working >=/ some one please help youll save alottt of time on my hands