Make sure your plug-in is copied to the plugins subdirectory where the mcjedi.bin is running. You can determine this directory with the following command:
Check that the plug-in is executable:
In the example above it is not executable ("x"). Add it this way:
If the plug-in is a Python script, make sure the first line specifies the path to the Python executable:
For a more complete example of creating and testing a plug-in, click here.