Λυχνία isn't quite that common in Greek. In fact, it's not common at all, and it's used in really specific cases, like λυχνία αυτοκινήτου, or ηλεκτρική λυχνία. You might see it in some Physics books too, but that's it. So you do understand that the originally added translations didn't include such specific terms, but simpler ones, that could be used a bit more often. (like λάμπα, or φωτιστικό). It's been added though. Thanks for the input. ^.^
Λάμπα is a lamp, meaning either the actual bulb or the whole device with the decorative bit. Φωτιστικό only refers to the whole thing - with or without the bulb. I often like to check such terms by running a google images search to see how the words are used, it can be illuminating! :D It's pretty clear in this case. Try λάμπα, then φωτιστικό, then λάμπα γραφείου and you'll see the meaning overlap.
I understand the only acceptable options are μια λάμπα or ενα φωτιστικό. In this exercise, I was to fill in the blank ι.ε. 'Ενα _____'. With the indefinite article 'ενα' already in place, the one and only acceptable answer is φωτιστικό. Conclusion: μια λάμπα/ενα φωτιστικό
I'm not sure I understand what you are asking. If you had the article ένα and you added "φωτιστικό" it would be correct.
"Μια λάμπα" is simply another way of saying this with a slight difference in meaning. See the above comments for more details.
Please let me know if there is something else you wanted clarified.
Sorry, but we moderators cannot see what you wrote. Did you check what the response was when it was rejected.
Did you perhaps use the wrong article...you needed "μια λάμπα" or "μία λάμπα".
Why don't you use the Drop down hints to assure that you always have the right translation.