You may take account for some nuances with the keywords selection. Here's, what can happen and what you need to do if they appear: NOT FOUND STATUS ?
This happens if an app can't be found by our users among TOP-250 apps for the desired keyword. !
Try to choose another, more detailed keyword by which your app is among TOP-250 on a certain market. *Note:
if you see that your app is «not found» by exact keyword but some installs were already delivered, it means that some users found it but most of them didn't. It may happen due to changes on the market, such as appearance of new competitors (as an example). You may try this keyword in some time again, but first, use more accessible keywords to promote.