When calling the "SetData" property with a single point, the clustering scripts fails (using the non-mini reference version of V7CientSideClutering.js) at line 173
 
pixel = _map.tryLocationToPixel(_data[i]._LatLong, Microsoft.Maps.PixelReference.control);
 
reason is that the SetData routine at line 326
 

        if (i > 0) {

 
should be

        if (i >= 0) {

 
With the original (if (i > 0)) , a single points count is equal to 0 and thus the _data[i]._LatLong property is not set which is needed for call at line 173.
I've corrected in my version but thought I would pass on my finding.
BTW, thanks for all your work and contributions. The code is awesome and works very well.
Thanks again
David