Cloud9 failure, exit code 100, possibly relate to tmux(?)

I am new to cloud9. Just created an environment and opened it. It seems installing several things to my EC2 (which I usually access using ssh from my PC at home) but eventually left below message in red and obviously failed. How can I fix this? (message) (~)/.c9/bin/tmux: error while loading shared libraries: libevent-2.1.so.7: cannot open shared object file: No such file or directory Installed tmux does not appear to work: exiting with 100

Failed Bash. Exit code 100.

One or more errors occured. Please try to resolve them and restart AWS Cloud9 or visit https://forums.aws.amazon.com/forum.jspa?forumID=268 (end of message)

Any information is welcome please.