Getting Timeout Exception while sending and Receiving Data , XBEE RF Sx

I am using Digi XBEE RF Sx to build an application Using Xbee Java Lib -1.2.1 ,
Device Configuration : Digi Mesh Network , API 1
Problem : I am Getting Timeout Exception while sending the Data and Recieving Data
com.digi.xbee.api.exceptions.TimeoutException: There was a timeout while executing the requested operation.
at com.digi.xbee.api.AbstractXBeeDevice.sendXBeePacket(
at com.digi.xbee.api.AbstractXBeeDevice.sendAndCheckXBeePacket(
at com.digi.xbee.api.XBeeDevice.sendData(
at com.digi.xbee.api.XBeeDevice.sendBroadcastData(

And also getting Exception of parsing
DataReader: Error parsing the API packet.
com.digi.xbee.api.exceptions.InvalidPacketException: Invalid checksum (expected 0xF2).
at com.digi.xbee.api.packet.XBeePacketParser.parsePacket(
So how I can solve this problem ?