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

Hi,
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(AbstractXBeeDevice.java:1340)
at com.digi.xbee.api.AbstractXBeeDevice.sendAndCheckXBeePacket(AbstractXBeeDevice.java:1504)
at com.digi.xbee.api.XBeeDevice.sendData(XBeeDevice.java:856)
at com.digi.xbee.api.XBeeDevice.sendBroadcastData(XBeeDevice.java:997)

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(XBeePacketParser.java:216)
at com.digi.xbee.api.connection.DataReader.run(DataReader.java:519)
So how I can solve this problem ?