From Strategy Page:
May 23, 2015: The “peace talks” with Iran remain stalled, this time because Iran refuses to allow inspections of military facilities.
The Iranian military leadership considers such inspections a legal excuse to spy on Iranian military operations.
Iran also wants 24 days’ notice before any inspections to verify that a treaty (that would halt Iranian nuclear weapons development and lift sanctions) was being followed.
Moreover the ruling clerics of Iran have come right out and said all sanctions must be lifted as soon as a deal is signed.
In the West getting the currently negotiated proposed deal approved is more complicated because of democracy and divisions in the leadership between those who want to do any kind of deal (just to be done with the economic and political problems caused by the sanctions) versus those who demand proof (intrusive and unscheduled inspections) of Iranian compliance.