public static void WorkingRoutine()
{
    Document famDoc; //This is within my family document.
    XYZ dir = XYZ.BasisX.Negate()
    XYZ norm = XYZ.BasisZ

    //This makes a 1/32" line.
    XYZ p = new XYZ(0,0,0);
    XYZ q = p + (.002605 * dir);

    Curve curve = Line.CreateBound(p, q);

    CurveArray array = new CurveArray();
    array.Append(curve);

    // we will get one of the Revit default profiles for Duct.  In this case, Duct - Round
    FamilySymbol orgProfileSym = null;
    GetProfileFamilySymbol(famDoc, out orgProfileSym);

    FamilySymbolProfile profile = famDoc.Application.Create.NewFamilySymbolProfile(orgProfileSym);

     //Sketch Plane
     Plane gPlane = famDoc.Application.Create.NewPlane(normal, p);
     SketchPlane sPlane = SketchPlane.Create(famDoc, gPlane);

     Sweep connSweep = famDoc.FamilyCreate.NewSweep(true, array, sPlane, profile, 0, ProfilePlaneLocation.Start);
}

// THIS IS THE ROUTINE THAT DOESNT WORK.
// It appears that copying the 'orgFamSym' value makes the Sweep not work.
// I need to figure out why.
public static void NonWorkingRoutine()
{
    Document famDoc; //This is within my family document.
    XYZ dir = XYZ.BasisX.Negate()
    XYZ norm = XYZ.BasisZ

    //This makes a 1/32" line.
    XYZ p = new XYZ(0,0,0);
    XYZ q = p + (.002605 * dir);

    Curve curve = Line.CreateBound(p, q);

    CurveArray array = new CurveArray();
    array.Append(curve);

    // we will get one of the Revit default profiles for Duct.  In this case, Duct - Round
    FamilySymbol orgProfileSym = null;
    GetProfileFamilySymbol(famDoc, out orgProfileSym);

    // In this instance, we will make a copy of that family symbol so we can have multiple connectors
    FamilySymbol profileSym = CreateNewConnProfileType(4, orgProfileSym)
    FamilySymbolProfile profile = famDoc.Application.Create.NewFamilySymbolProfile(profileSym);

     //Sketch Plane
     Plane gPlane = famDoc.Application.Create.NewPlane(normal, p);
     SketchPlane sPlane = SketchPlane.Create(famDoc, gPlane);

     Sweep connSweep = famDoc.FamilyCreate.NewSweep(true, array, sPlane, profile, 0, ProfilePlaneLocation.Start);
}

public static void GetProfileFamilySymbol(Document doc, out FamilySymbol sym)
{
    sym = null;
    string profileLocation = @"C:\ProgramData\Autodesk\RME\2014\Libraries\US Imperial\Duct\Fittings\Profiles\Duct - Round.rfa";

    doc.LoadFamilySymbol(profileLocation, "Duct - Round", out sym);

    if ((!sym.IsActive) && (sym != null))
    { sym.Activate(); doc.Regenerate(); }
}

public static FamilySymbol CreateNewConnProfileType(double diameter, orgType)
{
    string symName = "Conn 1";
    FamilySymbol rtnSym = orgType.Duplicate(symName) as FamilySymbol;

    SetParameter(diameter, ref rtnSym);

    return rtnSym;
}

 public static void SetParameter(string paramName, double paramValue, ref FamilySymbol sym)
{
            //This routine is in place because Revit 2016+ does not allow for the use of the Element.get_Parameter method.
            ParameterSet ps = sym.Parameters;

            foreach (Parameter p in ps)
            {
                if (p.Definition.Name == paramName)
                {
                    try { p.Set(paramValue); }
                    catch { }
                }
            }
}