If you are solving problems that affect more than yourself you will need the help of people to solve it and implement it.
To solve an issue you are going to need a variety of people in the room.
Creative thinkers, others with the power to sanction the go ahead for the solution.
Others might include those that had a hand in creating the problem, those with a direct vested interest in the solution or those who will actually have to implement the solution.
You might wish to consider people not related to the project that can stimulate ideas from a neutral position.
This diversity of experience will help fertilise fresh and innovative ideas.
How important is the meeting?
For example, if you need to make a critical decision there and then can someone present sign off for any actions?
How a meeting is organised and managed is critical to the successful outcome of problem solving.
Both the venue and the initial preparation need attention.