How to combine the solid

[623526308]

Hi

I want to use code to combine a seires of solids which were created by lost features.

my C# code a following (solid1-10 are loftfeatures)

 Inventor.ObjectCollection Combine2 = inventorApp.TransientObjects.CreateObjectCollection();
            Combine2.Add(solid2);
            Combine2.Add(solid3);
            Combine2.Add(solid4);
            Combine2.Add(solid5);
            Combine2.Add(solid6);
            Combine2.Add(solid7);
            Combine2.Add(solid8);
            Combine2.Add(solid9);
            Combine2.Add(solid10);
            var CombineCreate = compDef.Features.CombineFeatures.Add(solid1.SurfaceBody, Combine2, PartFeatureOperationEnum.kJoinOperation, true);

But it does not work. and the error message is Parameter Error in the last line.

I want to know how to make it correct.

Thank you.