How to set variable by input formula? (EPDM API)

Hello.

I want to realize following.

*PreCondition

Set input formula to Variable A.

The inupt formula is if set "AAA" to Variable A, set "BBB" Variable B.

*TOWANT

If set "AAA" to Variable A by EPDM API, set "BBB" Variable B automatically.

*Wrong Source...

The following source coutldn't realize.

    Private Sub ExeButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ExeButton.Click
        Dim vault As IEdmVault13 = New EdmVault5
        vault.LoginAuto(VaultsComboBox.Text, Me.Handle.ToInt32)

        Dim filePath As String
        filePath = "C:\testvault\Part1.SLDPRT"

        Dim fileObj As IEdmFile8
        fileObj = vault.GetFileFromPath(filePath)

        Dim enumVarObj As IEdmEnumeratorVariable9
        enumVarObj = fileObj.GetEnumeratorVariable(filePath)

        Dim getVarSuccess As Boolean
        Dim attrObj As Object = Nothing
        getVarSuccess = enumVarObj.GetVar("A", "", attrObj)
        enumVarObj.SetVar("A", "", "AAA", False)

        enumVarObj.CloseFile(True)

    End Sub

SolidworksApi macros