If the app is from the CommBox Store ensure you are connected to the internet and have enough internal storage on the CommBox. To check the storage available on your panel open the quick menu by pressing the small arrows on either side of the screen.
From here you can access the information about the panel from the bottom icon. You will see the amount of storage available on the panel as well as the memory space. Memory is the RAM used to run the applications whereas storage is the space the applications take up.
If there isn't much available free space on the panel try and delete some old applications. This can be done by pressing and holding the app until a little red X appears in the corner.
Once you have deleted some apps do a hard restart of the CommBox Panel by flicking the switch on the back of the panel off and on.