Describe 3 possible problems that an entrepreneur might have when constructing a business plan for a business?

I've got the overambitious bit, where the entrepreneur could make his fore-casted sales too high and then when sales are actually poor, they might not deal too good with the situation as it wasn't expected. Also I get the bit that the entrepreneur could be so focused on his business plan, it means too little time spent talking to customers or visiting suppliers.. i need one more problem?