Cannot display PrsDim_LengthDimension

I am trying to create a length dim in the 3dViewer.
I thought that is helpful to see my attachments file first.
That attachment file shows the result about these codes.

// Code Starts //
Handle(Geom_Point) handle_PointA = new Geom_CartesianPoint(messuare_PointA);
Handle(Geom_Point) handle_PointB = new Geom_CartesianPoint(messuare_PointB);

// -vvvv- Display SupportLine -vvvv- //
// Create A supportLine .This Line starts from PointA and PointB;
Handle(AIS_Line) ais_supportLine = new AIS_Line(handle_PointA, handle_PointB);
// Set the supprotLine color and width more clear
Quantity_Color c = Quantity_Color();
c.SetValues(Quantity_NOC_GREEN);
ais_supportLine->SetColor(c);
ais_supportLine->SetWidth(7);

myContext->Display(ais_supportLine, true);
// -^^^^- Display SupportLine -^^^^- //
// Code Ends //

Because I can actually see the green supportLine in my viewer.
So I can know that the PointA and PointB is actually the point that I wanted to select,and the way I display an InteractiveObject is also right.

So the way that I am trying to display a interactive object should be right.Beacuse I actually see the green line.

Now I am trying to show the lengthDim on my screen.
I noticed that class "PrsDim_LengthDimension" inherts from the class "AIS_InteractiveObject".After showing my support line correctly,It should be similar to show another InteractiveObject.

// Code Starts //
Handle(Geom_Point) handle_PointA = new Geom_CartesianPoint(messuare_PointA);
Handle(Geom_Point) handle_PointB = new Geom_CartesianPoint(messuare_PointB);
// -vvvv- Display PrsDIM -vvvv- //
// Get the Camera plane from camera data
gp_Pnt cameraCenter = myV3dView->Camera()->Center();
gp_Dir camera_Dir = myV3dView->Camera()->Direction();
gp_Pln cameraPlane = gp_Pln(cameraCenter, camera_Dir);
// Create our interactiveObject that display lengthDim
Handle(PrsDim_LengthDimension) dimAtCameraPlane = new PrsDim_LengthDimension(messuare_PointA, messuare_PointB, cameraPlane);
myContext->Display(dimAtCameraPlane, true);
// -^^^^- Display PrsDIM -^^^^- //
// Code Ends //

But I can not see the lengthDim on my screen.So I thought maybe the way I construct the PrsDim_LengthDimension is wrong.
so,I thought maybe i get trouble in meaning of the third the third argument in the constructor function:
PrsDim_LengthDimension::PrsDim_LengthDimension (
const gp_Pnt & theFirstPoint,
const gp_Pnt & theSecondPoint,
const gp_Pln & thePlane
).

The document said that " thePlane ------[in] the plane to orient dimension."

So ,I tried to use the ZNear plane and the ZFar plane like the code below

// Code Starts //
// Dim At ZNear Plane
Standard_Real zNear = myV3dView->Camera()->ZNear();
Standard_Real nearPointX = cameraCenter.X() + camera_Dir.X() * zNear;
Standard_Real nearPointY = cameraCenter.Y() + camera_Dir.Y() * zNear;
Standard_Real nearPointZ = cameraCenter.Z() + camera_Dir.Z() * zNear;
gp_Pnt pointAtNearPlane = gp_Pnt(nearPointX, nearPointY, nearPointZ);
gp_Pln nearPlane = gp_Pln(pointAtNearPlane, camera_Dir);
Handle(PrsDim_LengthDimension) dimAtNearPlane = new PrsDim_LengthDimension(messuare_PointA, messuare_PointB, nearPlane);
myContext->Display(dimAtNearPlane, true);
// Dim At ZFar Plane
Standard_Real zFar = myV3dView->Camera()->ZFar();
Standard_Real farPointX = cameraCenter.X() + camera_Dir.X() * zFar;
Standard_Real farPointY = cameraCenter.Y() + camera_Dir.Y() * zFar;
Standard_Real farPointZ = cameraCenter.Z() + camera_Dir.Z() * zFar;
gp_Pnt pointAtFarPlane = gp_Pnt(farPointX, farPointY, farPointZ);
gp_Pln farPlane = gp_Pln(pointAtFarPlane, camera_Dir);
Handle(PrsDim_LengthDimension) dimAtFarPlane = new PrsDim_LengthDimension(messuare_PointA, messuare_PointB, farPlane);
myContext->Display(dimAtFarPlane, true);
// Code Ends //

But I still can not see my dim on the screen.

Now I thought it's time to post my trouble at the fourm and seeking for your helps.
Any words from you guys can help me.
Thank you