We have some assemblies with patterns missing their driving feature information.  I don’t know how it was lost, but I’m writing an application that will warn the user if the information is missing.  I’m using SolidWorks 2010 SP 5.  The following code runs pre-save within an addin:

Imports SolidWorks.Interop.sldworks

Public Class clsPatterns

    Private model As IModelDoc2

    Public Sub New(ByVal swModel As IModelDoc2)

        model = swModel

    End Sub

    Public Sub FindUndrivenPatterns()

        Try

            Dim strFeatureName As String

            For Each objFeature As IFeature In model.FeatureManager.GetFeatures(True)

                If objFeature.Name.ToUpper.Contains("PATTERN") Then

                    strFeatureName = objFeature.GetTypeName2()

                    Select Case strFeatureName

                        Case "DerivedSketchPattern"

                            Dim objCurrentDefinition As IDerivedPatternFeatureData = objFeature.GetDefinition

                            Dim objPatternFeature As Feature = objCurrentDefinition.PatternFeature

                            If objPatternFeature Is Nothing Then

                                MsgBox("warning1")

                            End If

                        Case "LocalLPattern"

                            Dim objCurrentDefinition As ILocalLinearPatternFeatureData = objFeature.GetDefinition

                            Dim objAxis As Object = objCurrentDefinition.D1Axis

                            If objAxis Is Nothing Then

                                MsgBox("warning2")

                            End If

                        Case "LocalCirPattern"

                            Dim objCurrentDefinition As ILocalCircularPatternFeatureData = objFeature.GetDefinition

                            Dim objAxis As Object = objCurrentDefinition.Axis

                            If objAxis Is Nothing Then

                                MsgBox("warning3")

                            End If

                    End Select

                End If

            Next

        Catch ex As Exception

        End Try

    End Sub

End Class

I am having trouble returning a value for the PatternFeature property within the IDerivedPatternFeatureData interface and the Axis property within the ILocalCircularPatternFeatureData interface.  A value of Nothing is returned.  I’m using the same process for the D1Axis property in the ILocalLinearPatternFeatureData interface and this value is correctly returned.  I don’t seem to have an issue with any other properties of the three pattern interfaces I’m calling.

What might I be doing wrong?