This is actually a question I should've asked a while ago(as in, I don't even work at this job) but I thought it to be an interesting question nonetheless.
Our team was basically just 1 developer(me!). The manager also developed sometimes, but was mostly just business. He thought we should have some sort of bug tracker, so we installed some open source tracker on our server. I initially did not use this bug tracker.
Then, another developer was hired. He doubled as a tester(sometimes) and it seemed like every morning(His shift was scheduled like 2 hours earlier than mine by preference) I'd come into work, he'd have about 2 pieces of paper full of bugs and possible bugs. I'd go through each item, mark them off as a fixed them, or wrote by-design, or fix later.
Anyway, then I'd come in another morning.. another list of bugs. About 6 of the 15 bugs listed were duplicates, or extremely related to bugs I'd previously said by-design or fix-later on.
So, I started using the bug tracker on our server. It wasn't hard to use(required only a bug title), but it wasn't great either. I told the other developer that he should start entering bugs there and I will check the bugs he submits when I come in. This way it'd be easier to track.
I come in the next morning, and lo and behold another piece of paper on my desk listed with bugs. At this point about 11 out of 13 listed bugs were duplicates. I didn't even bother writing on the paper. (this continued basically for about 4 months, until I was layed off)
TL;DR: What should I have done to convince this other developer to use the bug tracker?