Did you configure your Linksys device to send the netflow data? You can verify that the LinkSys is configured to send netflow data by using a pack sniffer like wireshark to verify it is sending the packets out.
The SRW224G4 doesn't appear to support Netflow which would explain the issues you're having with the Realtime NetFlow traffic Analyzer. Below is a complete feature list for the SRW224G4 switch.
If you're interested in using the Real Time Netflow Traffic Analyzer with this device I would recommend looking at nProbe. More information can be found at the following link.