Mouse event wont update camera rotation in winforms

问题

My app has a custom panel used to display the XNA screen within a WinForm. I've currently displayed a test model with no problem and now working on camera movement. My camera is a Free Camera (not bound to look at any specific target), but I've been having trouble getting the mouse to update the yaw and pitch of the camera on its own axis. I thought maybe something was wrong with my update method, but that wasn't the case, because the camera updates moving forward and backwards using KeyboardState. But I have no idea as to why the MouseState isn't working.

FreeCamera.cs

using XNAButtonState = Microsoft.Xna.Framework.Input.ButtonState;
....
MouseState pastMouseState;
private float rotationSpeed_ = 1f / 60f;
private float yaw_, pitch_;
...

private void updateMatrix()
    {

        Matrix rotationMatrix = Matrix.CreateRotationX(pitch_) *
                                Matrix.CreateRotationY(yaw_);

        Vector3 forward = new Vector3(0, 0, 1);
        forward = Vector3.Transform(forward, rotationMatrix);

        viewMatrix_ = Matrix.CreateLookAt(Position, Position + forward, Up);
        projectionMatrix_ = Matrix.CreatePerspectiveFieldOfView(
            MathHelper.PiOver4, 16.0f / 9.0f, 0.1f, 100000.0f);
    }

 private void cameraInput()
    {
        KeyboardState keyboardState = Keyboard.GetState(); <-- updates
        currentMouseState = Mouse.GetState();              <-- not updating

        if (currentMouse.LeftButton == XNAButtonState.Pressed)         
            pitch_ -= rotationSpeed_;

        if (keyboardState.IsKeyDown(Keys.W))
            move(1);
        if (keyboardState.IsKeyDown(Keys.S))
            move(-1);

        pastMouseState = currentMouseState;
     }


public void update()
    {
        cameraInput();
        updateMatrix();