Translation:Where is Harajuku's train station?
doesn't include the word for "train" yet fails you for just putting in station. smh
If you posted your entire answer someone could tell you if your answer should have been accepted or if you made a different mistake.
If you're specifically looking for Harajuku Station, I agree with you, it should be "Harajuku Eki". But you could also be looking for another station in the Harajuku area (Meiji Jingu Mae Station is right nearby). In that case I think "Harajuku no eki" makes sense.
from what I remember, you just walk down harajuku's takeshita doori and it's at the very end of the road, you can't miss it lol