xbee with mega sensor shield(v2.0)

Does mega senor shield provide a fixed pin to xbee ?
When did not use mega shield to test, only use maga board ,xbee can successfully receive and send. But with mega shield , when connect to the xbee, tx suddenly bright , and continued

I have tested two mega shield ,both have this problem.

Please check your configuration setting.

When undering no mega shield to test, xbee can successfully receive and send

what is meant by this??

Sory,I mean did not use mega shield