WPF Populate DataGrid programmatically

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C#

WPF

DataGrid

I have a Page containing a DataGrid. I need to populate this from 2 separate sources. The 1st three columns of data I read from a text file (both the column headers, and the subsequent rows of data).
After that there is anywhere from 1 to 100 columns I need to add that will just contain checkboxes.
I'm creating the 1st 3 columns as type DataGridTextColumn, and the remaining columns I am creating as type DataGridCheckBoxColumn.
I *think* I'm doing this all correctly, except for three problems.

1. I can't SEE the data in the 1st 3 columns.

2. When I try to click on the Checkboxes in the remaining columns they don't Check / Uncheck

3. If I double-click the checkboxes I get an error - "EditItem is not allowed for this view.

Below is the code that creates this grid. When I created a Winforms version of this dialog, I trapped the CurrentCellDirtyStateChanged to commit the Checked/Unchecked state, and CellValueChanged to operate on the resulting change. That's part of my Checkboxes problem - I haven't found a WPF equivalent.
Any suggestions on how to solve my problems?

private void CreateMapSamplesToAssaysTable( )
{
    try
    {
        this.dgViewSamples.Items.Clear();
        this.dgViewSamples.Columns.Clear( );
        List<string> strColHeaders = new List<string>( );
        strColHeaders.Add( rm.GetString( "SampleIDColumnTitle" ) );
        strColHeaders.Add( rm.GetString( "SampleDescriptionColumnTitle" ) );
        strColHeaders.Add( rm.GetString( "DilutionFactorColumnTitle" ) );
        // Add columns and column header captions for the selected assays.
        int numAssays = data.SelectedAssays.Count;
        for( int nIdx = 0; nIdx < numAssays; nIdx++ )
        {
            string selectedAssayName = data.SelectedAssays[ nIdx ];
            strColHeaders.Add( selectedAssayName );
        }
        int nCols = strColHeaders.Count( );
        for( int nIdx = 0; nIdx < nCols; nIdx++ )
        {
            DataGridColumn col = null;
            switch( nIdx )
            {
                case 0:
                case 1:
                case 2:
                    col = new DataGridTextColumn( );
                    col.IsReadOnly = true;
                    break;
                default:
                    col = new DataGridCheckBoxColumn( );
                    col.IsReadOnly = false;
                    break;
            }
            col.Header = strColHeaders[ nIdx ];
            this.dgViewSamples.Columns.Add( col );
        }
        string strFileName = data.WorklistPath;
        StreamReader reader = new StreamReader( strFileName );
        string strLine = null;
        // Eat the first line, i.e. the column header
        strLine = reader.ReadLine( );
        while( ( strLine = reader.ReadLine( ) ) != null )
        {
            char[ ] chDelimiter = new char[ ] { '\t' };
            string[ ] strParts = strLine.Split( chDelimiter,
                StringSplitOptions.None );
            if( strParts.Length >= 3 )
            {
                string[] strRow = {strParts[0], strParts[1], strParts[2]};
                this.dgViewSamples.Items.Add( strRow );
            }
        }
        reader.Close( );
    }
    catch( Exception ex )
    {
        StackFrame sf = new StackFrame( );
        Errors.ErrorMessage( ex, sf, true );
    }
}</string></string>