By the way, setting up a public static variable like that so that anyone and your mother's brother's cousin's father's friend from high school can get to it is NOT a good practice. Try to keep the scope of variables as small as possible, so you maintain control on what happens to it. Otherwise, it's a free-for-all and you can run into some pretty nasty problems with that.
By naming the fully qualified name of the variable, you gave Java all the information it needed to locate it. You could have also fixed it by adding a static import of Shop.sc, not that it would be a good practice to do (see my last reply).