@debmar1 

Do you have a non-contact voltage tester?  If you do then I recommend the following:

• disable power to the switch
• remove the switch that is connected in this location
• For safety, put a wire nut on each exposed wire.  
• Turn the power back on
• Use the voltage tester to ensure the 2-black wires carry power. 

If they do then:

• Turn power back off 
• remove wire nuts and reconnect the HS200
• turn power back on and see if you can manually control the switch 
• If not then turn power back off and switch the two black wires 
• turn power back on and retest.  

If this fails as well or the wires do not carry power then I would suggest contacting an electrican.

debmar1 wrote

This switch is the only switch in the house that operates these lights. I pulled out switch and was attached to 2 blacks/1 white/1 green,

  @debmar1 that HAS to be a 3-way switch (in this case the white would be being used as a traveler along with one of the blacks). So although you are under impression that is the only switch, there must be another one somewhere. 
If you cannot locate it however, it really doesn't matter as you can utilize just that one switch but the wiring is not how you probably currently have it; 

As I suggest, that white is not going to be a Neutral (dumb switches simply do not EVER use Neutral Wires, only smart switches), but it is a traveler as is ONE of the black wires - the other black will be the line. 

So 

1. Identify which of the two black wires is truly the Line in; (that one should have been connected to the common of the original switch) - that goes to one terminal of the HS200 Line/Load

2. Identify which of the remaining two wires (one black, one white) actually turns on the light - this will be your load wire (it is not truly directly connected to the load, but a traveler which gets switched to the actual load at your 'other' unidentified switch. Cap with a wire-nut whichever is the other one (i.e. if you use the black, cap the white and vice versa) 

3. Use the ACTUAL Neutral that comes in with the Line Wire (NOT the one that was connected to the switch) for the HS200 Neutral Wire connection. This may be commoned with the other neutral wires inside that switch box. Ideally you use the one that comes in in the same romex as the Line Wire. 

For step 2, if you're not sure how to identify this, just 'guess' - i.e. go with the black wire and cap the white wire; if it works, great. If it does not, then connect the white wire to the load terminal and cap that other black.