I'm getting some trouble using the texture() method inside beginShape()/endShape() clause.

In the display()-method of my class TowerElement (a bar which is DYNAMIC), I draw the object like following:

void display(){
    Vec2 pos = level.getLevel().getBodyPixelCoord(body);
    float a = body.getAngle(); // needed for rotation

    pushMatrix();

    translate(pos.x, pos.y);
    rotate(-a); 

    fill(temp);    // temp is a color defined in the constructor
    stroke(0);

    beginShape();
    vertex(-w/2,-h/2);
    vertex(w/2,-h/2);
    vertex(w/2,h-h/2);
    vertex(-w/2,h-h/2);
    endShape(CLOSE);

    popMatrix();

}

Now, according to the API, I can use the texture() method inside the shape definition. Now when I remove the fill(temp) and put texture(img) (img is a PImage defined in the constructor), the stroke gets drawn, but the bar isn't filled and I get the warning

texture() is not available with this renderer

What can I do in order to use textures anyway? I don't even understand the error message, since I do not know much about different renderers.