Question. P7700 Commander mode.

Just tried built-in flash as a commander for SB-900. After some shots it stoped working. Anyone experiensed something like this? Maybe I have changed some settings accidentally, I don't know...Reset to factory settings didn't gave anything. I checked all flash settings - nothing.

B.t.w, what is the chanel/group should be set in a slave flash? Mine was Group A, Ch1 when it worked.

Any adwises?