Ok this is somewhat common. Labs can be bullheaded and love to see if you will chase them. IMPORTANT: Never chase! not saying you did, but this is just something not to do.

You didnt mess up terribly, but you never want to associate "come" with anything but praise... In scold mode, use something else, like "look what you did" or "whats the matter with you?" Only use "come" with a reward. The dog should want to come to you, if he gets yelled at or scolded and you have said "come"... He is going to remember that it means he is going to be punished. You follow?

E-collars are great tools. But there is no faster way to ruin a dog. You have to study up on how to use them succesfully. Dont get buttonitis. They are for corrections when the dog "KNOWS" the command and "CHOOSES" not to obey... You shouldnt "nick" a dog that doesnt know the command yet, for not obeying. If blaze "KNOWS" that "come" means to get his arse to your feet immediately, and decides hes not going to...then you wear his azz out. (nick him until hedecides to cometo you) Then give him lots of praise.

Hope this helps get you through, training is very frustrating one day, and very rewarding the next. Your doing a good job, just keep to it.

Good luck.