Why this sentence is wrong?

I see nothing wrong with the first sentence. Was your textbook written by a native speaker of the English language? The second sentence is just lame, i can't imagine any native speaker using a sentence such as that. I suggest to you that your textbook is wrong.

I agree with Setanta. The natural way for me to say this is
'We want you not only to be a useful member of society, but a responsible one.'

I second that agreement.

All those is favour say aye.

Eye

I