Had an interesting experience last week in the auto department at the one close to where I live. They had just opened a second register as the line was getting long at the first one. I was roughly three feet away from the display of blank keys, the two women working were at least five feet from the display and discussing what they needed to do next. One said they needed to get a blank key for an order they had to get done, then a key jumped right off the display and hit the floor to my right. When I said that was odd, they mentioned needing a key right before one jumped off the rack they looked surprised and said that kind of thing happens there pretty often.

Check the place out with Ghost Radar app.

Got the app, very unimpressed with it.

I wouldn't be surprised, negative energies and spirits would accumulate there. Well, in any Walmart. The lines are too long -.-

Wandered around with the Ghost Radar app on Thursday night. Got the same level of results I get at home, random words like opening a dictionary and picking the first word I see. None seemed related to any words I got before.

Ok, i little bit out of topic, but i had pretty nice experiences with Ghost radar, for example, this month i was watching vampire Diaries ( not a big fan of this series, it was just there in television, and i was feeling too lazy to look for something else,haha!)
Well, while Caroline character was talking, Ghost radar send EXACTLY this name: CAROLINE!!!
Then my Bf came home and we where watching a reality show, all of s sudden he said: "what is it with those people teeths?!?
Then Ghost radar send TEETH
Each time i use it, i always receive a message that is completely in phase about what is going on,
it will never help me about anything, it just shows me that i have spirits around, and they are watching what i do,lol!^^
Not of great help , but really fun!^^

And about your topic, i am not even surprised about the idea of a haunted Wal-Mart,
also, if you have high protection, maybe the walmart spirits/energy can't come next, if it have not a good intention towards you, in the end the lack of answear could even be reassuring!^^

I would definitely come back there to see if i could catch something,
best luck is you go ghost hunting again!^^