For the ocomms addon and the ocomms desktop app to communicate correctly, the correct combination of graphical settings must be configured. For most people this won't require any change, but in some situations a little noodling is required.
Thing you will want to check are:
- Is windows running in 32 bit color mode?
- Are you using any color blind support options in WoW?
- Are you using the UI scale options under advanced graphical settings?
Also, you will want to check that the ocomms addon and the ocomms desktop application are both using the same hotkey.
Click the cog wheel in the upper left of the ocomms application to open the settings. The default value for comms-key should be SEMICOLON.
Now in game hit escape to open the game menu. Select "Key Bindings", then select "AddOns" from the left side bar. Under the "oComms" heading you will have a setting for "Communications Key", which should be set to ; by default. Key 2 should say "Not Bound".
You can use any key as your "Communications Key", but it must be the same key that is configured on the oComms application.