What shortcode can I use to have the option of seeing next months on calendar?

I wanted to know what could be the reason for and/or how to fix this problem: https://premium.wpmudev.org/forums/topic/what-shortcode-can-i-use-to-have-the-option-of-seeing-next-months-on-calendar

I opened a new discussion topic because it has been a week since I replied and haven't heard anything since.

Thank you in advance!