TransitionDrawable not changing the color as expected

Question

I have the following in a class ProgressIndicatorView. The view, when used holds the five rectangles below :

When the user presses the button "Fortsæt" I call the views method setProgressIndicator(int step) which sets the color of the next rectangle in the view to fully opaque. The method looks like this :

public void setProgressIndicator(int activeStep) {
        // Fade IN
        TransitionDrawable transition = (TransitionDrawable) this.getChildAt(activeStep-1).getBackground();
        transition.startTransition(transitionTime);
}

and the init method looks like this

private void init(Context context) {
    this.setOrientation(LinearLayout.HORIZONTAL);

    transitionColor = getResources().getDrawable(R.drawable.colortransition);
    for (int i = 0; i < squareAmount; i++) {
        ImageView loadingPiece = new ImageView(context);
        //loadingPiece.setBackgroundColor(transparentWhite);
        loadingPiece.setBackgroundDrawable(transitionColor);
        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(0,
                LinearLayout.LayoutParams.FILL_PARENT, 1.0f);
        lp.setMargins(0, 15, 4, 15);
        this.addView(loadingPiece, lp);           
    }
}

The method works perfectly if I use a static backgroundcolor as the resource but doesn't when I use the transitioncolor drawable. Any suggestions as to what could be causing the issue ?

edit: for clarification THIS is what the view looks like when I use this.getChildAt(activeStep-1).setBackgroundColor(opaqueWhite);

but THIS is what it looks like when I use the current implementation of setProgressIndicator:

What is causing this to happen?

edit: Is there another approach that I could possibly to accomplish this effect if the cause of this problem cannot be located?