An economic downturn is a great time to start a business. Costs are lower, and more talent is available, thanks to layoffs. Prospective clients are more likely to try a new supplier who can help them cut costs or increase their competitiveness. Established players, too, are focused on cutting costs instead of increasing market share.

Still, most of the business plans these entrepreneurs generate fail to make much impression on potential investors, largely because they are written before enough real work has been done to create a solid foundation.

Why don't these business plans deliver? They don't include three key elements that go into a successful business plan: a logical statement of a problem and its solution; a battery of cold, hard evidence; and candor about the risks, gaps and other assumptions that might be proved wrong. This article exposes the deal-killers found in the five most commonly rejected types of business plans, and shares tips for creating plans that should get you invited back for a second meeting and, if all goes well, raise some capital and attract some initial customers.