i have this error in my code :One or more errors occurred during processing of command.

leDbConnection con = new OleDbConnection(); 
DataTable dt = new DataTable(); 
con.ConnectionString = "Provider=MSDAORA;Data Source=DATA;Password=**********;User ID=********"; 
con.Open(); 
string sqlcommand = "INSERT INTO GROUPS(GROUP_ID, GROUP_NAME,DEPT_ID) " + "VALUES(SEQ_MAX_GROUP_ID_NO.NEXTVAL,@groupName, SELECT DEPT_ID FROM PERSONNEL_TEMP.DEPARTMENT WHERE DEPARTMENT_NAME=@depName)"; 
OleDbCommand command = new OleDbCommand(sqlcommand, con); 
command.Parameters.AddWithValue("@groupName", textBox1.Text); 
command.Parameters.AddWithValue("@depName", comboBox1.SelectedItem); 
OleDbDataAdapter oda = new OleDbDataAdapter(command); 
oda.Fill(dt); 
dataGridView2.DataSource = dt; 
con.Close();