How to draw more than 4 cursors on a map?

For some reason I don't seem to be able to draw more than 4 cursors on a map.

Code:java

In MyRender.render():   
 
    for(int i=0; i<10; i++){
            MapCursor c = new MapCursor((byte)(i*20-100), (byte)(i*20-100), (byte)0, (byte)0, true);
            c.setType(Type.WHITE_CROSS);
            canvas.getCursors().addCursor(c);
        }
 

This code will never render more than exactly 4 cursors. Is this a limit and if so, is there a way to get around it?