AutoCAD Civil 3D :: Opening Object For Write Access

I'm upgrading some older COM based code to work in VB.Net with Civil 3D 2012. The app iterates through all of the Alignment objects, finding the ones with SuperEleveation, and places the names in a listbox. The user can select one or more of the alignments from the list to have the SuperElevation slope values modified. 

The problem I am having is when I get the alignment object to update I get an execption that the object is locked. It's probably something simple but I'm at a loss to where to go next.Here as a brief code snippet:

' Sub1 is called to find all of the alignment objects with SuperElevation
Sub Sub1()
Dim objCol As Autodesk.AutoCAD.DatabaseServices.ObjectIdCollection
Dim objID As Autodesk.AutoCAD.DatabaseServices.ObjectId
Dim tm As Autodesk.AutoCAD.DatabaseServices.Transaction
Dim myAlg as Alignment
[code]....