Walmart Grocery Stocker interview questions

Very short and friendly. Only asked one question. More of a conversation than an interview. I interviewed 3 days after applying and was immediately hired. Went in for orientation a couple days later.

Got called in for an interview at 2. Interviewed by 2 people, then they went to discuss me. They told me I was hired for grocery stocker. They called my references. I signed papers describing my duties and what my pay would be. I was sent to do a drug screen, and also signed permission for them to do a background check. Waited 2-3 hours for the drug screen. Finally took it and left. I was so sure I had the job, I went and bought two blue polo shirts to wear to work. Waited two weeks, no word from them. Went back to ask, and he said they were just waiting on my background check. Called back every two weeks, and was told the same thing. Found out the store was about to open, so called the store and was told they couldn't find my information, but something must've been wrong with my drug test or background check. Both should have come back perfectly clean. I think I just got lost in the system somehow.