Tracker issue database suggestion
Check back on my comments to your three previous questions on designing an accounting application schema (avoid cross and or repeat-posting BTW). 

Schema  design  is an iterative process. There must be a billion issue tracker programmes out there - search for "open source issue/bug/ticket/problem tracker" and you'll get loads of schemas with which to experiment.

Personal recommendation on this one, at least for initial study: D. Richard Hipp's bug tracker called Fossil - he uses an SQLite database to store the schema. From the Fossil site "Fossil is a simple, high-reliability, distributed software configuration management system" and the software that Hipp produces is stellar!

Look at those and then design your own schema. I don't know what development environment you're using, but take your first pass at a schema, and then run some code against it. Then fix the bugs (there will be bugs) and do the same thing again. Rinse and repeat until you get a programme that works to your own satisfaction.

If this is for some commercial need, then I suggest that you use an already available F/LOSS programme, unless your company has some compelling requirement that can only be fulfilled by a COTS product. You haven't mentioned any particular database server - that could be a factor in any choice of COTS and indeed F/LOSS. Some companies offer free products - Oracle has a bug tracker written in Apex for which the source is available and it's interface is very slick - your choices are virtually limitless in this domain.

If this is a school/uni project and your professor seems to enjoy handing out schema design projects (IMHO, a bookkeeping system is a bit much for a first project), then you should a) tell us this up front and b) show us that you have made some effort - which you have - your ERD above shows that you've at least thought about the problem.