Why my dumps keeps declining?

[mastercorp]

I’m still considered noobie I been working since middle November. However I have a problem why my dumps only work for small amounts. Example I can get 0-$60 items all day but soon as I try Walmart or footlocker for over $100 unable to complete credit transaction. And crazy thing is I go try the cards after that and they still work just can’t get big amounts. Is that because I’m swiping and hitting credit? All cards I get are in the same state but different cities so it can’t be region lock correct? What am I doing wrong I have lost thousands since November I’m on the verge of giving up due to the fact I’m not making nowhere near my money back. PLEASE HELP