LPC935 problem with re-programming

[Simon]

Hi
I have problems with re programing LPC935 when I change UCFG to extern crystal. I try to use extern crystal 4, 7.3728 and 11.0592 Mhz with cap 33pf. I look signal with osciloscope and they look OK. When I put new LPC935 I can program it if I set flash magic oscillator setings random (not 7.373) seting ?!?

TNX Simon