I just got it working.
I found a note on Keil site about uVision 1...

Now it's work perfectly.
I't only sufficient to link c51s.lib or c51l.lib to the project. Just add the right file to the source group.

The c file must have the #pragma src directive at the top.

Now, in the "options for filename.c file" there are various checkboxes.
Two of them are:
-generate .src file
-assemble .src file

I don't know why they're gray by default.
I just set them to black.

It now works hopefully.

Thanks for suggestions.