I'm attempting to allow a DataGridView to allow the user to edit fields (for simplicity's sake, let's say it's just Items, each of which can have a Condition, with allowable values taken from a second table [Conditions]

e.g.

Data Structure (simplified)

Items Table

ID (Primary key--not to be shown)
ItemNum
Qty
ConditionAbbrev (e.g. "New", "Used", "Recert") -- used as a key to an item in the Conditions table below

Conditions Table

ConditionAbbrev (e.g. "New", "Used", "Recert", etc.
ConditionDescription (lengthy description of condition)

Desired Appearance of Grid:

My Grid should look like:

Item #   Qty   Condition
123456   10    [ New  v]   <-- A drop-down
234567   55    [ Used v]   
345678   99    [ New  v]   
etc.

The Strategy:

I'm attempting to set this up by:

Binding the grid to the first Items table (grabbing the first three columns which contain the actual values of each line of the Items table)
Creating a new DataGridViewComboBoxColumn ("CondCombo") and binding all allowable items from the Conditions table to it,
Looping through the grid and setting the value of CondCombo for each row to the value of the Conditions row
Hiding the Conditions (text) column.

The Problem:

I'm able to get the column added and loaded with Conditions values, but I'm utterly failing at setting the selected value to match the Condition from the Items table; furthermore, any selections I'm making in a combo is being blanked the moment I tab or click to another cell.

Here's the code I've got so far: any help would be HUGELY appreciated!

Sub SetupGrid(byref myGrid as DataGridView, 
              myConn as sqlite.sqliteConnection)

    Dim myAdapter As System.Data.SQLite.SQLiteDataAdapter

    myGrid.VirtualMode = true
    myAdapter = new system.data.sqlite.sqliteadapter(_
        "Select ID, ItemNum, Qty, Condition FROM Items", myConn)
    myAdapter.SelectCommand.CommandType = CommandType.Text

    ' Fill the main grid with the item data
    dim ds as new DataSet
    myAdapter.Fill(ds)
    myGrid.DataSource = ds.Tables(0)

    ' Now create and load the ComboBox column
    dim cboColumn as new DataGridViewComboBoxColumn
    With cboColumn
        .DataPropertyName = "ConditionAbbrev"
        .name = "CondCombo"
        .HeaderText = "Cond"

        ' Bind the ComboColumn
        Dim conditionsAdapter As System.Data.SQLite.SQLiteDataAdapter
        Dim condTable As DataTable
        using cmd as new Sqlite.sqliteCommand(_
            "SELECT ConditionAbbrev FROM Conditions", myconn)
            conditionsAdapter.selectCommand = cmd
            conditionsApapter.fill(condTable)
         end using

         .DataSource = condTable
         .DataPropertyName = "ConditionAbbrev"
         .ValueMember = "ConditionAbbrev"
         .DisplayMember = .ValueMember
      end with

      ' Set the selected combo member to be the same as the Condition (text) field value:

      for each curRow as dataGridViewrow in myGrid.Rows()
          curRow.cells("CondCombo").value = _
              curRow.Cells("Condition").value
      next

      ' Hide the Condition (text) field)
      myGrid.Columns("Condition").visible = false

      ' Hide the ID field
      myGrid.Columns("ID").visible = false
end sub

You're setting the DataPropertyName incorrectly. You bind one list to the grid and one to the column. The DisplayMember and ValueMember are names of columns/properties of the items bound to the column. The DataPropertyName is the name of a column/property of the items bound to the grid. In your case, it looks to me like DataPropertyName should be set to "Condition".