This often means that the encoder that this Access Code connects you to is not online. You should contact the encoder's administrator and ask them to check the status of the encoder - it may be either offline, or it may not be connected to a valid audio or video source.
If you have a password to access the iCap Administrative site, you can confirm whether or not the encoder is online by going to the Access Code page and seeing if the name of the encoder appears in red in the display.
If you have never used iCap before from your current location, it is possible that you are being blocked by a firewall - ask your network administrator. iCap audio uses UDP, which is sometimes blocked on certain networks. The UDP port for iCap is 6900, and the traffic is initiated in the outbound direction.
Occasionally iCap data can also be blocked by the firewall or anti-virus software on your own computer. You may want to test by turning off your firewall and anti-virus temporarily and seeing if this helps (remember to turn it back on when you're done!). If it works only with the firewall or anti-virus software turned off, you should be able to use iCap with the anti-virus software on by adding iCap to the anti-virus software’s Exceptions or Safe-List.