Rt-server startup issue

Dears Experts,

I have installed rt-4.4.1 on debian-8.7. It has been installed successfully but somehow i am unable to start its service.

Following is the error while starting service.

root@rt-serv:~# /opt/rt4/sbin/rt-server --port 8080
[4429] [Thu May 4 05:27:05 2017] [critical]: Something went wrong while trying to run RT’s standalone web server:
Can’t locate object method “new” via package “Plack::Handler::Starlet” (perhaps you forgot to load “Plack::Handler::Starlet”?) at /usr/local/share/perl/5.20.2/Plack/Loader.pm line 47. (/opt/rt4/sbin/…/lib/RT.pm:390)
Something went wrong while trying to run RT’s standalone web server:
Can’t locate object method “new” via package “Plack::Handler::Starlet” (perhaps you forgot to load “Plack::Handler::Starlet”?) at /usr/local/share/perl/5.20.2/Plack/Loader.pm line 47.

As per the logs iformation, i added package package Plack::Handler::Starlet; in /usr/local/share/perl/5.20.2/Plack/Loader.pm file but it also not help. i am still facing following error even after loading Plack::Handler::Starlet package in Loader.pm.

/opt/rt4/sbin/rt-server --port 8080

[4457] [Thu May 4 05:34:42 2017] [critical]: Something went wrong while trying to run RT’s standalone web server:
Can’t locate object method “new” via package “Plack::Loader” at /usr/local/share/perl/5.20.2/Plack/Runner.pm line 220. (/opt/rt4/sbin/…/lib/RT.pm:390)
Something went wrong while trying to run RT’s standalone web server:
Can’t locate object method “new” via package “Plack::Loader” at /usr/local/share/perl/5.20.2/Plack/Runner.pm line 220.

Please review and suggest me the way forward. Thanks!

Dear Experts, I am waiting for your response…