Invalid selector argument XYZ in @e,@a,...

When using the selector argument XYZ (@e[X,Y,Z]) ex. '@e[998,20,548]' it's giving the error: "[...] You must specify which player you wish to perform this action on." Also this does'nt work if you add the 'r' (radius) (@e[r=..]) next to it. ex. '@e[998,20,548,r=5]'. So, it's broken (not the radius selector argument but the XYZ argument). Thanks for you're attention