C# - Getting Error 'Connection Property Has Not Been Initialized'?

I am getting error ExecuteReader: Connection property has not been initialized. below is the code i am using.

SqlDataReader oReader = new SqlDataReader();
string sSQL = @"
WITH TAB_CTE AS (
SELECT fbominum, fbompart, fparinum, flevel, fsono
FROM sodbom
WHERE fbompart= @fbompart and fsono = @fsono
UNION ALL
SELECT e.fbominum, e.fbompart, e.fparinum, e.flevel, e.fsono
FROM sodbom e
INNER JOIN TAB_CTE ecte ON ecte.fbominum = e.fparinum where e.fsono = @fsono
)
SELECT *
FROM TAB_CTE where fbompart <> @fbompart
";
SqlCommand oCommand = new SqlCommand(sSQL, this._connection);
oCommand.CommandType = System.Data.CommandType.Text;
oCommand.Parameters.Add("@fbompart", ItemSODBOM.fbompart);
oCommand.Parameters.Add("@fsono", ItemSODBOM.SONO);
oReader = oCommand.ExecuteReader();//Here I am getting error