C memory layout convention is raw-major, but this piece of code in plotHeatmap() assumes column-major:
Code
for(i=0; i<Cols; i++)
	  for(j=0; j<Rows; j++) {
		//print(TO_ANY,"\nHeat: Col=%i Raw=%i %.4f",i,j,Data[i*Rows+j]);
		plotGraph("Heat",i+1,-j-1,SQUARE|STATS,color(Data[i*Rows+j]*100./Scale,BLUE,RED,0,0));
}
accessing incorrect elements of Data