Error message

The message below is shown while running my simulation on proteus... can anyone help me out to solve this problem ...

The message is telling you that the ADC period you are trying to use is less than the minimum specified for that particular IC. Try reducing the sampling frequency.

There is no error!!! ISIS has just determined that the input impedance on the ADC may / may not be correct for the settings you have used..

If you are sampling a steady (ish) voltage, pay it no mind!!!