codec loopback problem on lcdk OMAP L138 kit

I am facing the following problem on the LCDK kit for OMAP L138:

I have 4 no. of LCDK kits. Only on one kit CODEC loopback is working. The file I am using for testing comes with the STARTERWARE for OMAP l138 in the foder titled "binary " containing the .out files generated for testing purposes. The mcasp example is being used for loopback of line_in to line_out.If some hardware problem is  there in the dac path or adc path where to look at and how to debug .Please provide suggestions...

Thanks and Regards

KAUSHAL KUMAR