Nadya,
I've recently hit this wall too, spent hours trying to figure it out. Doing everything you did over and over. Now I just remove the code from my project (after deleting all .FXP's) and recompile everything (recompile all), choosing ignore when asked to locate it. Then I recompile a second time (no need to recompile all this time), locating it when asked. I can then, usually, see the code in the trace window. Tedious but it seems to work.
If I were the super careful kind of guy I use Mark's method but I'm afraid that I'd do what he said it's easy to do - mixed up the code. (hehehe...)

BTW, are you using VFP7 ? Do you remember this happening in earlier versions?