You appear to have a USB to Serial adaptor. The Generic USB-serial cables many times give "problems"

I Might suggest you buy the REAL "Uniden USB programming cable" - you can get them from Uniden,

or from people like Bearcat Warehouse. 877-568-SCAN
        Hobby Radio Stop  - 1-937-299-7226

But - FIRST. / / try this......

Connect cable to PC and Radio

Set ALL "TIMING" settings to "ZERO timing" and then CHECK ON "Load/read speed"

Turn radio OFF, then Turn back ON.

The "state" the radio is in when turned on is the state that will accept 'commands' from the computer. It "Should" work and read the systems in the radio. The reason I mention this is some people have the radio in "MENU" mode and that simply will not work... at all.

If it does NOT read it, I usually suspect the driver for the cable is not working properly. This can be difficult to track down sometimes, and ONE easy way to is to try installation on a 2nd computer if you have one, and see if the same reading errors occur.

It NOT, then you know where to look, such as Uninstall/reinstall the driver etc. on the problem computer.

If it DOES NOT work then contact the manufacturer of the USB/Serial cable (or Uniden ir "their" cable) and see if they have newer drivers etc... especially if you're running Windows 7

Using Uniden 396XT with USB to Serial cnx.  Auto detect finds correct scanner on port 6, 115K,8,1,N.
I select accept.  When I select systems in radio button, I get too many errors / check your connections message in form caption.
Any suggestions.  If auto detect finds correct scanner on correct port, then cnx must be ok, right?  I have tried setting higher delay values, all the way up to 0.1, but still get too many errors.
This is a new scanner, USB to Serial cable, etc.