I have a 4-way setup with 3 dumb switches and I would like to make the series smart.  I need to replace only one of the switches with the HS210 to make this happen.  I understand it is ideal to have the first switch that comes from the panel be the HS210 so it has constant power and the rest will be dumb.  Based on the configuration of my house, it is more convenient to have the last switch (ie, the load switch) be the HS210.  With the 2 traveler wires, one should be carrying power at all times to the last switch.  This setup works fine for most of the time.  Occassionaly (once a week), the lights flicker by turning on/off rapidly when either the dumb switches are turned from on to off.  Once I turn the dumb switch back to "on", the lights work fine.  I then have to use the HS210 to turn off and everything is fine.  Since the HS210 works most of the time, it should be getting power.  Any ideas on why the flickering?  Putting the HS210 as the first switch is not an option so hoping to make this work.