AutoCAD .NET :: Assign Plotstyle To Attribute Definition In Block?

I am trying to assign a plotstyle to attribute while creating a block. First I create the block, then I insert the Blockref, in that process I have errors assigining a plotstyle to the attribute. (I have also tried to assign the plotstyle while creating the block and attribute with poor results.)

Here is my attempt to do this:

For Each objId As ObjectId In blkTblR
Dim obj As DBObject = objId.GetObject(OpenMode.ForRead)
If TypeOf obj Is AttributeDefinition Then

[Code].....