That's the error I get when I try to load a custom component where I want to operate over a surface. 

I have tried to load the surface as Surface, NurbsSurface and BrepFace.

Code goes this way:

protected override void SolveInstance(IGH_DataAccess DA) {           

Brep myBrep= null;                                  

if (DA.GetData<Brep>(0, ref myBrep))           

{               

int U = 0;               

int V = 0;

if (!DA.GetData(1, ref U)) { return; }               

if (!DA.GetData(2, ref V)) { return; }

Point3d[,] colec = new Point3d[U + 1, V + 1];

double paramU = 0.0;               

double paramV = 0.0;

BrepFace mySrf = myBrep.Faces[0];

mySrf.SetDomain(0, new Interval(0.0,1.0));                   

mySrf.SetDomain(1, new Interval(0.0,1.0));                                       

for (int j = 0; j <= U; j++){

paramU = j * (1.0 / U);                                                      

for (int k = 0; k <= V; k++) { 
                           paramV = k * (1.0 / V);
                           colec[j, k] = new Point3d((mySrf.PointAt(paramU, paramV).X), (mySrf.PointAt(paramU, paramV).Y), (mySrf.PointAt(paramU, paramV).Z));                          }

                    }

.....

I have been able to reproduce this inside a C# Script component without problems. Any clue?

Thank you!