It sounds like one of your panels is twisted. Set the tip up at some angle, then measure the root with the incidence meter. They should both be the same. If they are not then either replace the panel, or attempt to twist it back to alignment, if possible. The re-twist needs to be permanent. If none of these solutions is possible, then you have to make a judgment as to how much this twist will affect the lateral trim of the model, will the tip being out a little have more effect than the root being out a little? On a straight, constant chord wing it will, on a highly tapered wing, it won't. So when you glue the panels together, either set the root the same as the other wing, or set the tip, or somewhere between the two depending on the amount of taper of the panel. The end result is to try to have the average wing chord line set the same as the other panel, so that there is as little difference in average AOA between each wing panel as you can get. It will be a compromise, at the stall angle one tip will be at a slightly different angle than the other so the stall will not be symmetric, but it is probably the best compromise you can get.
Evan, WB #12.