Translation:Finland is not in Scandinavia, but Norway is.
I have a feeling that would only work if you changed the topic and focus of the sentence like:
Skandinaviassa ei ole Suomi vaan Norja. "What's in Scandinavia is not Finland but Norway." (For example, if there's a multiple choice question "Which one of these countries is in Scandinavia?" and someone has chosen Finland instead of the only right option, Norway.)