I'm writing something, but encountered a problem. I thought of writing in the following way:

His lecture focuses not only on the deteriation of the enviroment but also on the measures to improve it.

Meanwhile, I consider wether it will be better to say "His lecture focuses on not only the deteriation of the enviroment but also the measures to improve it."

I think you can see the difference. The latter one put "not only...but also..." after "on" while the former one applies the other way around.

I'm non-native speaker. So I hope to be enlighted on the above issue. Thank you a lot.
Hello, Anon,

I prefer the first sentence, but there are typos: It's "deterioration" and "environment".
Tks for your comments. But are there any reasons for prefer of the former one?