Sounds like you mean its giving the error as soon as you enter the airway on the left side ae?
This is most likely the AIRAC database doesn't have H384 in it, therefore it doesn't think there is a airway comeing from TR so its saying you have enterd it incorectly. I'm not entiryly sure where to get a up to date (or at least somewhat complet) AIRAC for that model, maby the feelthere site? Just have a look around..
I would definatly say the AIRAC
If that doesn't fix it have a look at the Level D 763 manual,
here. Great manual for FMC operation
James