Problem regarding EDMA - mcbsp - PCM mUX transfer

Hi all you geeks out there. 
DSP 6482 is used here.  I am working on a s/w where an edma channel is
transfering data to a mcbsp port which forwards it to PCM MUX. 
Then using PCM MUX loopback, it is received at another mcbsp port from
where it read by another edma channel and transferred onto a buffer. 
Now when i compare data at sending and receiving buffers, the data doesn't
matches. But when i use DLB(digital loop back), data matches. Any ideas on
what could be the reason??? Clock is provided by PCM MUX. 
Plz reply 
Mandy