Although you are pushing the wattage limits of that in-line module, that shouldn't be the problem. Have you confirmed that the x10 signals are getting to the module? Do you have a phase coupler? That would be the first thing I would make sure of.

Next thing I would check is for noise. If the signal is getting there and the noise levels are OK, I would try to switch out the inline module.

Martin
Martin@AutomatedOutlet.com