vncsnapshot stuck with message - Zero size rect - ignoring

[puneet336]

Hi ,
I am using CentOS 6.9 and here is the issue i am facing with vncsnapshot tool -

bin/vncsnapshot 127.0.0.1:70 s.jpeg
VNC server supports protocol version 3.8 (viewer 3.3)
Password:
VNC authentication succeeded
Desktop name "server1.com:70 (spunit)"
Connected to VNC server, using protocol version 3.3
VNC server default format:
32 bits per pixel.
Least significant byte first in each pixel.
True colour: max red 255 green 255 blue 255, shift red 16 green 8 blue 0
32 bits per pixel.
Least significant byte first in each pixel.
True colour: max red 255 green 255 blue 255, shift red 0 green 8 blue 16
Same machine: preferring raw encoding
Zero size rect - ignoring

The program remains stuck here.
Please advice.