I can't install extension

[wjs33]

hi,

Weewx is running, with Belchertown skin. Mosquitto MQTT server running......i want install mqtt extension, but it happen this:

sudo wee_extension --install weewx-mqtt.zip
Request to install 'weewx-mqtt.zip'
Extracting from zip archive weewx-mqtt.zip
Traceback (most recent call last):
File "/usr/share/weewx/wee_extension", line 88, in
main()
File "/usr/share/weewx/wee_extension", line 80, in main
ext.install_extension(options.install)
File "/usr/share/weewx/weecfg/extension.py", line 123, in install_extension
self.install_from_dir(extension_dir)
File "/usr/share/weewx/weecfg/extension.py", line 194, in install_from_dir
extension_name)
File "/usr/share/weewx/weecfg/extension.py", line 249, in _inject_config
self.config_dict['StdReport']['HTML_ROOT'])
File "/usr/lib/python2.7/dist-packages/configobj.py", line 554, in getitem
val = dict.getitem(self, key)
KeyError: 'HTML_ROOT'

What could be the problem?

Thanks

Best Regards

Walter