Mod apk is a modified apk of the original, it may not compatible with all devices, so some device must can not use it. You may find the same mod, some users work well, but someone can not run it.
2.What should you do.
HappyMod's mods were uploaded by users, we want to provide a platform to let more and more users to try the mod and find the best one. The best one also means can work well on most of the users. 100% working mods is our goal. If the mod you downloaded can not run, please request it, follow this tutorial.
If nobody upload it, the status of it will be "coming soon", then you have to wait , it may take days, months or years, depends on when there has person upload it.
So please wait with patient, and we will be glad if you can comment the mod in happymod with your using details, that will help more and more people to find the best work one.