Why should we not trust Pakistan ?

In the past two days we have seen Pakistan's president Mr.Zardari say there is no Pakistani hand in the Mumbai attack whatsoever. Which does not surprise me.

He turned down India's demand to handover its most wanted terrorists who are relaxing in their safe havens inside Pakistan. That does not surprise me either.

Instead he asks India to share with him the evidence it has so he can try them in a court of law in Pakistan and have them punished. This does surprise me. Why ? Two reasons.

Reason 1:

All these years Pakistan has denied that a man by the name Dawood Ibrahim resides in Pakistan despite repeated requests/demands by the Indian Government. But yesterday, quite contrastingly, he refuses to handover the terrorists instead of denying their existence in pakistan which is nothing less than admitting their existence in Pakistan.

Reason 2:

What has Pakistan done when the father of its missile program was accused of proliferation ? They did not deny it but put him under 'house arrest'. They deny IAEA access to the arrested former scientist. He has never been investigated despite the issue here being something as grave as Nuclear proliferation.

Now asking India to provide/share evidence on Mumbai attacks with a promise of action against culprits does not stand a reason. Who are you trying to bluff Mr. President ?