Looking at you other posting regarding the line tool, I understand you now: you mean that the OnMouseMove is not triggered while the mouse button is held down. This is true - and not expected.
Some debugging shows that, as you suspected, this is related to the builtin toolset providing the built-in zooming and panning capabilities. Obviously, even if AllowZoom is false, the MouseMove of the tool gets fired and catches the event off of the chart.
I don't know too much about the internal operation of the toolset to fix this behavior. I'll try what I can do, but I don't promise anything...
But I saw in the source of TAGraph that the builtin toolset is created by a public function OnInitBuiltInTool which is implemented in TATools to create a zoom and a pan tool. So, if you want to get rid of this behavior re-implement that function in your uLineTool unit in a way as you require:
unit uLineTool;
...
function NoBuiltinTools(AChart: TChart): TBasicChartToolset;
begin
Result := TChartToolset.Create(AChart);
// This is just an empty toolset. No more builtin tools to catch events
// A first attempt to use nil for the result crashes the application.
end;
initialization
OnInitBuiltinTools := @NoBuiltinTools;
end.