ChartTimePriceToXY() vs. Pixels

I have found the function ChartTimePriceToXY() to be quite useful but exploring in more detail there may be some discrepancies.

Pick a candle using Time[] then use the code below to show the position of the candle as a percentage down the chart calculated using Time/Price & Pixels.

I would have thought the factor's should have been the same - see printout.

Is my code wrong or is it the inaccuracy of the platform?

(please can someone tell me how to exit the code window when I have entered code to continue below - it's driving me crazy!)

int start()
{      
 int x,y;
 ChartTimePriceToXY(0,0,Time[33],iClose(NULL,0,33),x,y);
 //calculate how far down the chart candle 33 is using time/price
 double diff_price = (WindowPriceMax() - WindowPriceMin())/(WindowPriceMax()-iClose(NULL,0,33));
 Print(1/diff_price);

 //calculate how far down the chart candle 33 is using pixels
 double y1 = y;
 double factor = NormalizeDouble(y1/ChartGetInteger(0,CHART_HEIGHT_IN_PIXELS,0),4);
 PrintFormat(factor);
}