LPC935FDH Can only program first time

[laps]

 have just made a circuit base on the mcb900 and have tried programming
a LPC935FDH in this circuit. It worked the first time, however when I tried to re-program
it again it would not work and I recieved a unable to communicate message from flashmagic.
Any suggestions on what I am doing wrong

[Andy Ayre]

Brand new devices reset into the bootloader. Programmed devices do not.

You are probably failing to start the bootloader. Check with a scope that three pulses are being received on the reset pin after power on.

Andy