I have been trying to update material properties to custom materials which I have followed this example for:

2018 SOLIDWORKS API Help - Set Material Example (C#)

swPart = (SldWorks.PartDoc)swModel;
// Get the material schema and names
// of available materials databases
vMatDBarr = (object[])swApp.GetMaterialDatabases();
Debug.Print("Material schema pathname = " + swApp.GetMaterialSchemaPathName());
for (i = 0; i < vMatDBarr.Length; i++)
{
Debug.Print(" Material database: " + vMatDB);
}
Debug.Print("");
Bodies = (object[])swPart.GetBodies2((int)swBodyType_e.swAllBodies, false);
for (j = 0; j < Bodies.Length; j++)
{
swBody = (SldWorks.Body2)Bodies[j];
// Get the name of the body
Debug.Print(swBody.Name);
// Set the SOLIDWORKS material for that body
swBody.Select2(false, null);
BodyMaterialError = swBody.SetMaterialProperty("Default", "LinktoMaterials", "AISI 304 Stainless Steel");
// Get the names of the body's material and the database to which it belongs
sMatName = swBody.GetMaterialPropertyName("", out sMatDB);
if (string.IsNullOrEmpty(sMatName))
{
Debug.Print("Body " + j + "'s material name: No material applied");
}
else
{
Debug.Print("Body " + j + "'s material name: " + sMatName);
Debug.Print("Body " + j + "'s material database: " + sMatDB);
Debug.Print(" ");
}
}

The code is finding the correct database and material name but it isn't applying it to the part.

"BodyMaterialError" is returning a value of 1 ( swBodyMaterialApplicationError_NoError 1 )

During the last IF statement it returns my database and material name which is correct but the material is still not updating:

Can anyone point me in the right direction as to what I'm doing incorrectly?