Starting in reporting services 2008 there is a new feature called On Demand processing.
With this feature reports may be rendered only one page at a time to speed up processing. One drawback to this can be seen on large reports. On your action bar, you may see page 1 of 2?
Here is an example:
One trick to avoid this is to add a textbox in your report header or footer. On the properties of the textbox, set Hidden=True. For the expressoin of the textbox, set it to =Globals!TotalPages.
Now when the report runs, it figures out the total number of pages to put into this textbox. And as a result, it also puts the correct number in your action bar!