Zombie apps are products that are never used or downloaded by anyone, and there are plenty out there, unloved, hiding on an Apple or Google server, waiting to be claimed. Many of them are perfectly good apps, but simply fail to take off for a variety of reasons, explained below.
Failing to offer any value
No one will download your app if there's no reason for them to do so. From the app's title, to the product description, your app needs to sell itself in the few seconds that someone might glance at it. Business apps needs to appeal to an audience, so your app should refer to those people from simple concepts like "Manager's time saver wizard" to "Essential tools for IT workers!".
It looks like a poor product
No matter how quickly you want to get an app to the market place, spend plenty of time getting the user interface and design into an attractive and usable state. If someone sees a screenshot of a cheap or over-complicated looking app, they will move on to another one, even if it isn't as good. In the app age, products need to simple and appealing, with obvious functionality. If your best feature is hidden in a menu, it is in the wrong place.
No marketing (it doesn't have to cost)
Even if your app is only designed for a select market, you still need to tell people about it to ensure that these people download it. Spread the word directly to your customers and clients via your website and products. Share news of the app via press releases, forum posts and messages in the places that it needs to be seen. If it is a wider-focused app then you need to let websites that cover apps know about it, but we'd draw the line at having to pay for coverage. If this app is your first product, then you need maximum effort on marketing via all means to get the word out there.
Be seen in the right places
Apps thrive on versatility, so if you can create a tablet specific version of your app, then do so to add extra value and usability. If your app can work on a smartwatch, then these will be big news in 2015, making it worth investigating. Finally, while your product/company may have a Windows focus, 51% of new devices activated over Christmas were iOS models, so don't stick with what you know for historical reasons, spread the net as wide as you can.