No oil everything clean and what's the correct angle?
Sorry just got back on and saw your post, you will have to experiment with the angle of the flint, try what Ron pa said and sometimes the frizzen has a coating from the factory on it try shining it up with a light sandpaper or steel wool
After hunting in rain a few times and wet days I had problems. Came to realize in months later I had my action go off but it would stop just as it got to the frizzen. The screw that holds on the frizzen to the pan was rusted. So I carefuly removed it and KABOOOM when I shot it next time. I think English flints if properly adjusted are best. If you oil any moving parts be sure to wipe all excess. I also take rubbing alchahol and wipe pan/flint/frizzen to remove any oil from your skin.
I have found you want you flint to strike the frizzen about 1/3 of the way down from the top or higher. Lyman's cut agate flints are sized to do that. Knapped flints might be too short, as I have experienced.
If the flint isn't striking soon enough try shimming it out a bit.