Diablo 2 Expansion - Import Character HELP


I was playing the barbarian in Diablo 2 on Nightmare Mode and had him at Level 43. I installed the expansion pack, picked a new character and played her for a bit. Now I want to play my old character but he doesn't show up as one of the characters I can select. Only the new person I created is there. I went to the Diablo II folder and the Save folder and the files are there for both characters so why can't I use my old character?! HELP!!

There should be a botton on there that says convert to expansion... If you are not able to see your character then go into open battle.net and he should be there... select him and exit out and back to the single player menu. now your character should be there...

Thank you Josh. Going into Battle.Net worked like a charm.