Is this the system you're trying to scan?
Pinellas County Public Services Trunking System, Pinellas County, Florida - Scanner Frequencies
That is a rebanded system. More on rebanding can be found here
While the Pro-164 will
handle a rebanded system, it's not quite as straight forward as entering the frequencies and talkgroups.
First, your scanner must be at firmware version 1.06 or higher (I believe the current version is 1.08). Second, you must set the system (in the scanner) to use the custom tables required for rebanded systems. For your model scanner, that can only be done via software like ARC300, PSREdit300, or Win97. That also requires the pc interface cable to connect the scanner to the pc. More on how to check the firmware, and also the software entries required, can be found in the Wiki
Also, note that the Pinellas system is labeled as 'mixed mode', so some talkgroups are analog (labeled with an "A"), which your 164 will receive. But there are a few labeled with a D
(for Digital) in the "Mode" column. Those digital talkgroups cannot be monitored by your scanner. A large number of the talkgroups are not noted either way. Somebody in the Florida Forum may have better information on how many, if any, of those might be digital as well.