Start problem with CC2480

Hi, we need help concerning the CC2480 startup. We build a Board with CC2480 and a host microcontroller. After resetting the CC2480 the SRDY signal falls to low and a a little bit later it raise to high. We make a compare measuring with the ZigBee Kit eZ430-RF2480. After a reset we can measure that SRDY falls from high to low and a little bit later it raise up from low to high. After a short period SRDY falls down from high to low. A little bit later it raise to high. It seems to be that the voltage regulators do not work proberly. We can only measure 0.6 V. We are not able to find our fealure. Is anybody here who can help us? Thanks.