Fails to select the points on "cloud" frame

[robotAtWork007]

Thank you @ankitdhall for this awesome tool. Its going to be damn useful for my project as a start point.

I am facing some difficulty marking the points on "cloud" frame. After successfully detecting the Aruco Markers, there are two pop-up windows, one for "cloud" and other for "polygon". When I start selecting points on "cloud", most of the times the following message is displayed on the terminal.

and the program terminates.

Also, One thing I noticed was the after selecting four points with mouse click and key press, a green line appears on the "polygon" window. Only sometimes there are red points on the green line. Also, on selecting the first edge, all other points start appearing blue on the "polygon" window.

I am wondering if some one else has encountered this and has a potential solution for this. Thanks!