Problem: Rendering an Object with setting own transformations

for my AR project i want to render a Cube. The position of the cube is dependent of perspective where I look at the marker. The cube should overlay the marker when I look through the glasses.
Currently the cube is rendered in both of my renderWindows (for each eye one), but the cube is moved to the top left or top right of the marker depending on which renderwindow.

When I look at the marker:

The ModelView Matrix and the ProjectionMatrix do i set like in OpenGL.
To use my own Modelview Matrix and ProjectionMatrix i took following functions:

SetModelTransformMatrix(F_EW_L); WorldToEye
SetExplicitProjectionTransformMatrix(F_CE_L); EyeToClip

and to render them in my camera I went with this:


Transformations and calculations should be right.
Does someone has an idea how to solve this problem with this wrong rendered cube? Maybe an hidden function that influence the transformations what I should turn off of something like this.

Thank you for your help!