Problem with xbee s2c and AT command

I try to control xbee s2c with AT command via USART from ST microprocessor. I send tab[] = “+++”, and nothing I don’t get receive, then I send “+++\r”, nothing. I found on google that sometimes good idea is send “X” before send “+++”, I try it too, and nothing happens. I check on oscilloscope that signals goes to xbee and it goes all is okey.

Mayby somebody know what is wrong, what I should to doo?