[Plugin: Timeline For Categories] Error Message

I like the idea but when I install this plugin, immediately at the top of the plugin screen after the install, I get this error.

Warning: session_start() [function.session-start]: Cannot send session cache limiter – headers already sent (output started at /home/content/25/5853525/html/wp-content/plugins/timeline-for-categories/timeline-for-categories.php:1) in /home/content/25/5853525/html/wp-content/plugins/tumblrize/tumblrize.php on line 58

I figured it had a problem with my Tumblrize plugin so I deactivated it. When I did, I then get the error mentioned in the notes

The plugin generated 3 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.

So I disregard it like the notes say but when I go back to my categories and try to put them in chronological order, I get

Warning: Cannot modify header information – headers already sent by (output started at /home/content/25/5853525/html/wp-content/plugins/timeline-for-categories/timeline-for-categories.php:1) in /home/content/25/5853525/html/wp-includes/pluggable.php on line 881

I didn’t carry it further this time but a while back I was messing with this plugin and disregarding the error messages but every time I added a category, it threw an error message. So I backed out and deactivated it.

I love the idea but hopefully it can get fixed.

https://www.ads-software.com/extend/plugins/timeline-for-categories/