how to configure radio registers of cc2500 and cc2511 to 250 Kbps and 500 Kbps?
your CC2500's Xtal frequency cannot be 2410MHz.. It should be 26 to 27MHz, per your crystal.
Check the actual frequency of both source and target, make sure the difference between them is within specifications (80ppm max).
TI's EE community is a better place for such questions.