You thought you did everything possible to plan your brainstorming session so your team would generate lots of awesome ideas.

But now that you've gotten started, you realize that the session is failing. Some participants aren't . . . well, participating. A few loudmouths are doing all the talking. And nobody is coming up with any viable ideas.

Can this brainstorm be saved? Absolutely, says Brian Cole Miller, author of Quick Brainstorming Activities for Busy Managers.

What doesn't work is to keep doing what you've been doing and hope that participants will snap out of it and suddenly become inspired. Instead, you need to reboot and try a new approach to facilitate the session.

Before I provide suggestions to address the most common brainstorming problems, let me spend a moment sharing one of my most important strategies for facilitation: plan carefully, then be prepared when things don't go accordingly to plan. Human dynamics are unpredictable--and an exercise that you thought would engage participants may fail miserably. So you need to have a Plan B, a Plan C and even a Plan D for those situations in which Plan A is a bust.

Miller's book is very helpful for building your strategy to facilitate a brainstorming session. Another book I rely on for inspiration is Gamestorming by Dave Gray, Sunni Brown and James Macanufo. For example, I've used a Gamestorming game called Campfire to help employees learn about an topic.

But when things don't go according to plan, here are 15 ideas for solving brainstorming challenges:

First challenge: People hang back and don't participate.

1. Break the group into smaller teams. Shy people are often reluctant to speak up in a large group, so making teams small helps loosen things up.

2. "Change the activity," advises Miller, "Perhaps using one where participants write their ideas first."

3. If people in the group are criticizing others or denigrating their ideas, remind participants that one of the core rules of brainstorming is not to judge or critique. Be sensitive to negative body language as well.

Second challenge: Some people dominate the discussion.

4. Miller advises distinguishing "between those who are truly dominating and those who are merely loud but still helpful and respectful," If someone is monopolizing the session in a negative way, ask him/her to hold off briefly to allow others to contribute.

5. Make sure that you use a mix of exercises--some that encourage people to participate verbally (for instance, calling out an idea), while others require writing, building something, creating posters and other non-verbal participation.

6. As in #2, change the size of teams. Over the course of one brainstorming workshop, I'm likely to break the group into teams of six to eight, to split those teams into three-person pods, and even to ask people to pair up in teams of two. Mixing it up alters the interpersonal dynamics.

Third challenge: Participants struggle to generate ideas.

7. Introduce a getting-to-know-you icebreaker to help lower inhibitions and/or jump-start the group. Usually, an icebreaker exercise is used at the beginning of a session, but you can bring it in anytime you need it.

8. Remain positive even if the energy is grinding to a halt. Be encouraging, but don't feel compelled to break a silence or solve the problem. Help participants work through the obstacle.

9. Throw an imaginary cat. I love this exercise from Gabriel Aldez, director at the product development engineering firm Simplexity. Ask six or eight people to stand up and form a circle. Give them two instructions: Try not to do anything interesting or creative. Second, be fast and don't overthink.

Say that you have an imaginary tennis ball that you are throwing into the circle. As you throw the ball, ask participants to pass it around and play with it, describing what they are doing. In a few minutes, turn the ball into a feather. And a few minutes later, turn the feather into a cat.

Encourage participants to act fast and keep talking. What will happen is that people will get creative (despite the instruction not to). When Aldez facilitated the exercise with students, "One student dribbled the imaginary ball between his legs, like a basketball player. Another threw the feather way up in the air and everyone waited patiently for it to come down. A third person gave the cat a tight hug." The exercise helps unleash creativity and loosen everyone up.

Fourth challenge: The same ideas are repeated over and over.

10. "This sometimes happens," writes Miller, "when a spectacular idea was given and the participants can't seem to get off it." If that's the case, make a point of recording the idea--I often create a flipchart page just about that concept and put stars around it--and remind participants that we've captured that one; now we need to generate others.

11. Another reason participants repeat ideas is that they're worn out and have nothing left to give. Miller suggests taking a stretch break of even a full-time out break to help people reboot.

12. After participants take a break, give them a completely new activity to do. This is a great time to introduce props or toys. I like marble run, the toy where participants build tracks for marbles to go through tunnels, down stairs, around centrifugal funnels and around windmills. The point is to let participants use a different part of their brains.

Fifth challenge: None of the ideas achieves your objective.

13. If you notice this happening partway through the session, go back and restate the objective. Make sure everyone is clear about what you're trying to accomplish.

14. Ask the group what's going wrong. Does anyone have an idea about how to get on track?

15. Review the ideas that have been generated to see what can be salvaged or built upon. Chances are, one or more ideas actually have potential; they just need work to become viable.