If all you have is a business plan, that might be your issue. There's also other sites like Angel List www.angel.co that will let you setup a profile and try and get in front of investors .. but without a solid team, some kind of prototype, early customer interest, etc .. it's tough.

Just look at the companies who did get funded and see how well you stack against them. Compare their numbers, team, product, etc and see if you're as good? If not, investors will just put their money in others who are.

Only 1200 companies per year raise venture capital, and I would assume 100x that try, so you need to standout.

Alternatively, you can try raising money from friends & family, future customers (crowdfunding, or pre-sales), etc.

Hope that helps.