Is it Creating Problem for Googlebot?

Hallo,

I am using robots.txt for blocking affiliate pages of my site.

do you think that Blocking more and more pages in robots.txt for Googlebot, is it creating a problem for my site?

Due to this problem, is it possible that my ranking in Google will be gone down?

Because there is affiliate urls are increasing more and more and for protecting my site from the penalty of Duplicate content i have blocked all affiliate urls in robots.txt and even any new affiliate url generate that will also block in robots.txt

I am using this command for blocking my affiliate urls:

User-agent: *
Disallow: /*?a_aid
Disallow: /*?

Because before implementing this command in robots.txt my ranking is very well but after blocking these kind of pages in robots.txt, I found that my ranking gone down.

so now what i should to do for getting my ranking up.

Let me know your suggestions.

Thanks

I feel that nofollow links would be a better strategy than disallowing in robots.

If you have a serious duplication problem you should look more closely into consolidating content if possible, as opposed to maintaining duplicate content and then trying to pretend, in a sense, as if it's not duplicate.