it would help if you tell us where you live as there are thousands of walmarts, not to be rude or anything. alsao you may want to try the FRS and/or GMRS frequencies, that is where you will most likely find the store you want, most stores operate on those frequencies
One aspect of this hobby is that it allows you to do your own research. I do not have your type of scanner but I am most certain that it has a search function. By turning this one you can search for the desired freq's yourself and then you can inform all of us.
Walmart is a subject that comes up quite often. I know someone suggested a Google search, but a search of our own thread history turned up quite a few threads (31 including yours) on the subject. Some were about Walmart freqs and some were not, but you may find that what you're looking for has already been covered and the frequencies given.