PIC24FV32KA301 - measuring Vdd using band gap voltage (gmorfeus)

Hi, I am trying to measure (estimate) Vdd by using Vbg on PIC24FV32KA301 and I use this function:UINT16 adcMeasureSingle() {
UINT16 result;
AD1CON1 = 0x0470;
AD1CON2 = 0x0000;
AD1CON3 = 0x0100;
AD1CON5 = 0x0010;

w..