I have welded this job before...even though it was troublesome....for whatever reason. but today it just wont wet out!

this is an unknown allow of alluminum sheet..it was made into a guard. it is about .0625 thick

I am using a miller dialarc hfp 300 amp machine... I have it set for AC, 40-165 amps set at 40%, and i use a foot control!! I am using a genuine helicar torch , thats water cooled with a 3/32" dia pure tungsten electrode. the gas is argon set to about 30 psi

i have used several rods...in 1/16th dia of 4043.

the material wets for a split second only then glazes over and I cant get my filler rod to stick...then the whole surface starts to sink....you all know..

what can i do to get this material to wet out more so i can add filler???

with out caving in