Functions giving different result with same parameters - google-maps

Question

I use GMLib to work with Google maps and now I have come to a point where I am very confused.
I have the functions GetDistance and GetHeading to calculate the distance and compass direction between 2 markers on my map.
When I call them from my procedure GetHeadingDistance I get the result I expect (distance and direction is correct)- aSearchCallInfo is a class containing info that needs to be updated with the values.
Now I am trying to add a function that lets the user press the right mouse button on the map and the get info about that location.
But in this case I get very wrong results. As far as I can see of the results it uses GMMarker.Items[1].Position as source even when I know that it is GMMarker.Items[0].Position I send as parameter.
When I try to debug the functions by writing values to a textfile during calculation, I can see that it is the correct values it gets to work with at the correct position.
(GMMarker.Items[0].Position is the position of the user of the software)
Any ideas as what I could try to get this solved?
procedure TfrmQthMap.GMMapRightClick(Sender: TObject; LatLng: TLatLng; X, Y: Double);
var
MessageText: string;
LL: TLatLng;
Heading: double;
Distance: double;
Qra: string;
begin
if GMMarker.Count > 0 then
begin
LL := TLatLng.Create;
try
LL.Lat := LatLng.Lat;
LL.Lng := LatLng.Lng;
Heading := GetHeading(GMMarker.Items[0].Position, LL);
Distance := GetDistance(GMMarker.Items[0].Position, LL);
Qra := Maidenhead(LatLng.LngToStr, LatLng.LatToStr);
finally
FreeAndNil(LL);
end;
MessageText := 'Data for det sted du klikkede på: ' + sLineBreak + sLineBreak +
Format('Længdegrad: %s', [LatLng.LngToStr(Precision)]) + sLineBreak +
Format('Breddegrad: %s', [LatLng.LatToStr(Precision)]) + sLineBreak +
Format('Afstand: %6.1f km', [Distance]) + sLineBreak +
Format('Retning: %6.1f °', [Heading]) + sLineBreak +
Format('Lokator: %s', [Qra]);
ShowMessage(MessageText);
end;
end;
procedure TfrmQthMap.GetHeadingDistance(aSearchCallInfo: TCallInfo);
var
Heading: double;
Distance: double;
begin
if GMMarker.Count > 1 then
begin
Heading := GetHeading(GMMarker.Items[0].Position, GMMarker.Items[1].Position);
Distance := GetDistance(GMMarker.Items[0].Position, GMMarker.Items[1].Position);
barFooter.Panels[PanelDist].Text := Format('Afstand: %6.1f km', [Distance]);
barFooter.Panels[PanelDir].Text := Format('Retning: %6.1f°', [Heading]);
aSearchCallInfo.Distance := Format('%6.1f km', [Distance]);
aSearchCallInfo.Heading := Format('%6.1f °', [Heading]);
aSearchCallInfo.SaveToDatabase;
end;
end;
function TfrmQthMap.GetDistance(aOrigin, aDest: TLatLng): double;
var
Distance: double;
begin
Distance := TGeometry.ComputeDistanceBetween(GMMap, aOrigin, aDest);
Distance := Distance / 1000;
Result := Distance;
end;
function TfrmQthMap.GetHeading(aOrigin, aDest: TLatLng): double;
var
Heading: double;
begin
Heading := TGeometry.ComputeHeading(GMMap, aOrigin, aDest);
Heading := 180 + Heading;
Result := Heading;
end;