inserting double number into data table

i use this query to insert data

cmd = new OleDbCommand("insert into avoir_note  values ('" + 
       comboBoxA.Text + "','" + comboBoxCM.Text + "','" + 
       comboBoxCE.Text + "','" + textBoxMat.Text + "'," +
       Convert.ToDouble(textBoxNote.Text)+ ",'" + 
       dateTimePickerDT.Text + "') ", Program.cn)

if i type for exemple 10 in textBoxNote it s work but

if i type for exemple 10,15 in textBoxNote i get this error The number of query values ​​must match the number of fields destination. if i type for exemple 10.15 in textBoxNote i get this error input string was not in correct format