C# - Forms - Access Database - insert variables

i want to insert data in my Access database. But this error comes up:

System.Data.OleDb.OleDbException
  HResult=0x80040E14
  Nachricht = Syntaxerror in INSERT INTO-command.
  Quelle = System.Data
  Stapelüberwachung:
   bei 

I have a class:

public static void inDatabase(string name_, string nachname, string benutzername, string email_, string hash, string salt)
    {
        OleDbConnection con = new OleDbConnection("Provider = Microsoft.ACE.OLEDB.12.0; Data Source = C:\\Users\\hahmann\\source\\repos\\ALB\\ALB\\data\\ALB.accdb");
        OleDbCommand cmd = con.CreateCommand();
        con.Open();
        cmd.CommandText = "Insert into user(Name_, Nachname, Benutzername, E-Mail, Hash, Salt)Values('" + name_ + "','" + nachname + "','" + benutzername +  "','" + email_ + "','"  + hash +  "','" + salt + "')";
        cmd.Connection = con;
        cmd.ExecuteNonQuery();
        MessageBox.Show("Record Submitted", "Congrats");
        con.Close();

All the variables comes from textboxes.