Getting a response as NULL in receiving end

hai this is surendra, i need a small information about xbee.
My objective is i need to read the data from slave device.
For this i connected first XBEE module to my microcontroller(Master)and it is transmitting some string .I need to get that same string in my slave device.

I have already tried that but i am getting the response in the slave device NULL what is the problem for that?Here i connected the slave XBEE to my PC to check the data from the microcntroller(i.e MASTER XBEE).where i am doing the mistake.Every thing is fine by the AT commands
PANID,ATMY,ATDL,ATBD,ATWR
Please give a feed back as soon as possible.
THank u

Try taking the processor out of the equation and just use XCTU to send your data with. Does that work? By doing this, you are able to verify if the issue is within your Code or what you think you are sending for data.