Pump action having difficulty extracting rounds

Hi everyone (new to shotguns) I bought a new pump action last week, didn't do anything to it other than put it together and in my bag. Brought it out to the range today, loaded up just fine, but for the life of me I could not get the round to extract after being fired. Flagged down the range help and he was able to get it out and then lubed up the gun we tinkered around with it and when he felt confident everything was better we put it down. Put another round through it like 10-15 minutes after that, same problem happened. He got it out and asked if I did anything since getting it and I told him no. He said to completely strip it down and take some care of it tonight when I get home. Anyone have any advice on what I should do or why this could be happening?