Map API - adding cursors

Can anyone show me proper way to add cursors to the map?

When I add cursor, it will display a map with a cursor for a moment, but then it will disconnect me with bad packet error with random packet number (always different).

Code:java

MapCursorCollection cursors = canvas.getCursors();
cursors.addCursor(20, 20, (byte) 1, (byte) 1, true);