Points from shapefile do not show up after being merged with other shapefiles

Hello all,

I am having a problem trying to do a very simple merger of a number of shapefiles that all contain simple X Y points. When I merge the six shapefiles that I am trying to merge, it creates a new shapefile with no error message whatsoever. However, it only contains points from five of the six shapefiles. No matter what I seem to do, merged shapefiles do not seem to contain points from this shapefile. Has anyone encountered anything similar to this?

Thank You.

--Evan