Multiple equilibrium arrows in marvin sketch

Hi, folks

I'm using the academic license in Marvin Sketch (thanks for that!), but I'm unable to draw multiple equilibrium arrows (⇌).

Am I doing something wrong?

Do the followings:

1. Select equilibrium arrow in the arrow combo box on the toolbar (or from the Insert / Arrow menu on the main menu).

2. Move the mouse to the canvas. Push the right mouse button where you would like to place the start point of the arrow.

3. Move the mouse and release the mouse button where zou would like to place the end point of the arrow.

But you can put only one equilibrium arrow to the canvas.

Thank you.