PIC24FJ256GA106 ADC problem (KDN)

AD1CON1 = 0x00E0; // auto convert after end of sampling
AD1CSSLbits.CSSL5 = 1; // no scanning required
AD1CON3 = 0b0001111100000010; // max sample time = 31Tad, Tad = 2 x Tcy = 125ns >75ns
AD1CON2 = 0; // use MUXA, AVss and AV..