Need a formula that checks to see if cells are empty

I have multiple cells that are linked to radio buttons. When a radio button is selected the cell linked to it is populated with a number depending on the radio button from a group that is selected. E.g if the first radio button is selected the linked cell is populated with a 1. I have multiple cells linked to multiple groups of radio buttons. If the user attempts to run a piece of code I have created with any of the linked cells are blank because the user did not select a radio button in one of the groups the system crashes. I need a formula that checks if a range of cells is empty and if so does not run the code but instead displays a message box to inform the user. I have given the cells that are linked to the radio buttons a named range they are called "Buttons".