Logic Pro 7 Controller Assignment Bug? Options

[camarao]

I'm having this annoying problem and I don't know if it is a bug or if it is something that I'm doing wrong.
I have Logic Pro 7, an M-Audio MIDI patchbay (4 ins 4 outs) and a Clavia Nord Lead 2, Waldorf Xtk, Yamaha FS1R and Yamaha 01V mixer, with all the MIDI ins and outs connected.
I mainly use the Clavia Nord Lead 2 as my MIDI controller. When I do, for example, a "learn controller assignment" for the ES1 filter cutoff, using the Nord Lead's own filter cutoff knob, it works for the ES1. But when I return to the Nord Lead track and try to modulate the Nord Lead's cutoff, nothing happens. It seem that the ES1 stole that controller for itself. Everytime I assign a controller for some kind of plug-in, that controller no longer works for the "real" hardware controler to control their own parameters. Did it happened to you also?
What am I doing wrong here ?