"The evidence proves that the sanctions were working."

It depends what you mean. For years the europeans [french, germany, and russian] wanted to lift the sanctions. Were they wrong?

What really worked was that the America coalition to get Saddam out of Kuwait was successful and at the conclusion of that war had a cease fire agreement which insisted that Saddam regime give up all it's weapons of mass destruction and the agreement had a means of verifying that Saddam comply with this agreement [so that if was in fact more than just a piece of paper describing a unrealistic goal].

Now, Saddam before he invaded Kuwait had already signed international agreements not to have nuclear and chemical and biological weapons [his use of long range missiles in the Gulf war as terror weapons *cost him* the inclusion of a ban of long range missiles]; therefore this agreement was considered *reasonable* and hard weasel out of by not agreeing to this as part of the cease fire agreement. *If Saddam had actually followed the cease fire agreement there wouldn't have been a need for sanctions*. Sanctions were a consequent of the failure of Saddam complying with the cease fire agreement, therefore for sanctions to "work" the result would be that Saddam would decide to comply with the cease fire agreement. THEREFORE it is FALSE to say that the "sanctions were working" [for them to work, it would cause Saddam to follow the cease fire agreement {which he never completely did}].
Perhaps, if you understood that sanctions are a form of warfare, you wouldn't see 12 years of sanctions as "evidence proves that the sanctions were working" and only requiring more years of this kind of warfare as a "good" solution.

What was working in regard to Saddam was the US miltary- the use of force and the threat of use of force was the main factor that forced Saddam to at least pretend that he was complying with his agreement. What "worked" was a cease fire agreement enforced by US miltary power, which demanded that UN inspectors be able to freely move about the country verifying that declarations of the regime regarding it's WMD was accurate.