Larison explains why:
The Green movement may want to appropriate the Egyptian and Tunisian uprisings as inspirational models for their own struggle, but that doesn’t mean that they can obtain the same result. For that matter, it has never been clear that all of the Green movement supported full regime change of the sort that Tunisians and Egyptians have been demanding.
Some in the movement may want that, but if the Green movement is best understood as an Iranian civil rights movement rather than a revolutionary one it does not even have the same political goal that opponents of Ben Ali and Mubarak had. To the extent that their opposition has focused on Ahmadinejad rather than on the entire system, their political goals are much more limited. As long as the movement’s leaders remain committed to Iran’s form of government, the success of the Iranian opposition in securing some political reforms will not directly lead to the toppling of the Iranian regime and it may never result in this.
We'll see what shape the new regimes take in Tunisia and Egypt, and I understand that Tehran, unlike Cairo and Tunis, is run by blood-thirsty Islamofascists who think nothing of mass murder of civilians, but I wonder what part of "Death To Khamenei!" Daniel doesn't understand?