How come do Aamir use no Udit Narayan as its singing voice in movies?

How come do Aamir use no Udit Narayan as its singing voice in movies?JustaFan closed in NaachGaana convex with 3 opinions see nocomments... Udit did rather many all songs in Lagaan (except ChaleChalo). He did JAANE KYUN in DCH. In man Galle Pandey, he did DEKHOAYE HOLI and that was it. Nothing in RDB, FANAA and not even BUM BUMBOLE in TZP (some lips synch song in complete movie). I mean it forUdit bad enough was that no one else has used him but no.