If the IP address found for the finder ID is correct, then your firewall could be blocking access. Either allow JSBR through your firewall, or if the slingbox on the same network you are running JSBR on use the local IP address instead of the finder id.
If the IP address found for the finder ID is not correct, then enter the correct IP address.
The software see my slingbox as 'available', but then says it cannot be located:
Searching for xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Slingbox is available at xxx.xxx.xxx.xxx:5001
Logging in as guest
A SlingBox could not be located at xxx.xxx.xxx.xxx:5001
Please follow the connection and problem solving guide for SlingMedia's SlingPlayer to ensure your SlingBox and internet connection are configured correctly.
Setting ID3 tags if appropriate
Comment: Captured with Jaksta Recorder for Slingbox - www.jaksta.com
Complete with errors
I can view the slingbox just fine on the standalone slingplayer (v220.127.116.112) on windows 7/8/10.