Trying to associate .TIFF files with program not working

I've been trying to associate .TIFF files with a program called PaperPort Image Viewer on one of my company's engineering computers. When I try to use the "Open With" function or the associate file type in Default Programs, the program does not populate in the window. I go and search for the executable for the program, select it and try to bring it into the window for acceptabel programs for the...