Gridded2DSet of Lat/Lon

I'm trying to create a Gridded2DSet of Lat and Lon values
but the constructor throws an Exception: "samples do not
form a valid grid".  I'm using the following constructor...

public Gridded2DSet( MathType type, float[][] samples, int lengthX, 
int lengthY)

My Lat/Lon values are on a Lambert Conformal grid projection, 
but I haven't defined the Coordinate System because I didn't
think it was necesssary (and it seems complicated -- there are
alot of parameters associated with a Lambert Conformal projection).

My float[][] samples are loaded from files such that 
samples[0][] = latitudes and samples[1][] = longitudes (reversing
these doesn't avoid the exception).

I've looked at the Gridded2DSet code to try to figure out why my
"samples do not form a valid grid" but I don't understand the 
algorithm that determines this.

Has anyone else had this problem or could someone explain to me
the algorithm that says my grid is not be valid?