I am trying to remove duplcates from a combobox however this doesn't seem to result in a correct combobox, since he fill the combobox with the following text.

"System.Linq.Enumerable+d__64`1[System.Char]"

I have the following code and are using a access database with generated datasets.

Code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Linq.Expressions;

namespace Generator
{
        private void matGroupBindingNavigatorSaveItem_Click(object sender, EventArgs e)
        {
            this.Validate();
            this.matGroupBindingSource.EndEdit();
            this.tableAdapterManager.UpdateAll(this.matGroupDataSet);
        }
        private void frmImport_Load(object sender, EventArgs e)
        {
            this.matGroupTableAdapter.Fill(this.materialGroupDataSet.MatGroup);

            //Distinct
            var BaseM = materialGroupDataSet.MatGroup.Select(row => row["BaseMs"].ToString().Distinct());
            foreach (var BaseMs in BaseM)
            {
               cmbBaseMat.Items.Add(BaseMs);
            }

        }
I have 3 comboboxes that i want to fill with data from the database. CoboBox 1 is filled with data and then it the removes the doubles (duplicates). When i select a value from ComboBox 1 it will update CoboBox2 with the possible choices based on ComboBox 1 and if I select a value from ComboBox 2 it fills ComboBox3 with resulting data.

I'm now first trying to filter out the duplicates.