Insert 1 Document Into Another Document - A part into an assembly drawing

[hollertrek]

I know this code references Autodesk Inventor (CAD) API, but I'm hoping for a generic solution to my problem with the following error. The error is "object reference not set to an instance of an object" and the macro takes an open document (part file drawing) and inserts it into another open document (assembly file).

Code:

        ' Set a reference to the assembly component definintion.
        ' This assumes an assembly document is open.
        Dim oAsmCompDef As AssemblyComponentDefinition
        oAsmCompDef = ThisApplication.ActiveDocument.ComponentDefinition

        ' Set a reference to the transient geometry object.
        Dim oTG As TransientGeometry
        oTG = ThisApplication.TransientGeometry

        ' Create a matrix. A new matrix is initialized with an identity matrix.
        Dim oMatrix As Matrix
        oMatrix = oTG.CreateMatrix

        ' Add the occurrence.
        Dim oOcc As ComponentOccurrence
        oOcc = oAsmCompDef.Occurrences.Add(sFileName, oMatrix)

Hopefully this is not too specialized to receive help in this forum.

Thx,
Jon

[hollertrek]

Ok, let me simplify my explanation of what's going on. I get "Object variable or With block variable not set" when trying to execute the following that refers to the active document. I’ve also gotten the error, which is related, “object reference not set to an instance of an object.”

Dim oAsmCompDef As Inventor.Assemb lyComponentDefi nition
oAsmCompDef = ThisApplication .ActiveDocument .ComponentDefin ition

Any idea why this would be happening?

Jon