QADC in MPC565 not accepting changing waveforms

Hi
  This is my first experiment with QADC.I have noticed following 
problems
1)When analog input is grounded, I am getting 78 Hex in Result table
2)When input is open  value in result table is 3FF Hex
3)Most importantly , when sqare wave of any frequncy is connected to 
analog input pin ,voltage is shooting to 5V .Hence not able to check 
QADC performance with varying analog input.

I am working with AXIOM 565 Evaluation board CMD5XX. 
Plz guide me with your valuable suggestions


with regards
umamahesh