Building and zoning question?

My friend genie applied for a permit from building and zoning to build a storage building to keep all her items. after going through all of what she needed many inspections to make sure everything was on point she got the permit.later she decided she wanted to make it into a small store so she applied for a business license and got it.now the sign needs to go up so people can know about the store .she called zoning so they can see the sign so she can get approval for that to.Well after lots of money. sweat and all the rest, zoning says she cannot have a store cannot open it, would be a violation, is not a commercial area and it is not zoned for that and had she told them she planned to make it a store they would have told her. i say it's a load of crock they do what they want.she was trying to do her little part for herself and the economy. to me doesn't seem fair. i know there are rules and regulations but this i do not understand do you have suggestions for my friend she is really distraught trying to figure this thing out is this what happens when you try to do things the right way. now she has spent all this money and can't open. why can't you have your building what you want it to be, there are houses and stores around her why can't she put hers.How would you argue this. THIS IS NOT RIGHT.