Thanks for all the great advice. I took the plane to Ace Hardware at lunch yesterday and had them put a steeper angle on the blade and that helped a lot.
Then I stood back and looked at the side of the panel I was trying to plane and it is indeed a long, concave curve. Duh!

So I'm moving on to other panels with my block plane and ordering the Veritas low angle spokeshave, which I've wanted anyway. :-) Of course while I'm ordering, I may as well get the Veritas Sharpening System, which I've also coveted,(and small-blade holder for the spokeshave) so I can sharpen my plane correctly. Gotta love excuses to buy tools, don't you?

Patsy