execute stored procedure (with parameters) with an "exec" command

Hi everybody, I would like to know if it's possible to execute a stored procedure, passing it parameters, using not CommandType.StoredProcedure value of sqlcommand, but CommandType.Text.

I tried to use this:
sqlCmd.CommandType = CommandType.Text
sqlCmd.Parameters.Add(sqlPar)
sqlCmd.ExecuteNonQuery()

With this sql command:
"exec sp ..."

I wasn't able to make it to work, and I don't know if it's possible.

Another question:
if it's not possible, how can I pass a Null value to stored procedure?
This code:
sqlPar = new SqlParameter("@.id", SqlDbType.Int)
sqlPar.Direction = ParameterDirection.Output
cmd.Parameters.Add(sqlPar)

sqlPar = new SqlParameter("@.parent_id", DBNull)
cmd.Parameters.Add(sqlPar)

doesn't work, 'cause I get this error:
BC30684: 'DBNull' is a type and cannot be used as an expression.

How can I solve this?
Bye and thanks in advance.

P.S. I would prefer first method to call a stored procedure ('cause I could call it with 'exec sp null' sql command, solving the other problem), but obviusly if it's possible...=)

Sorry for grammatical mistakes.It's DBNull.Value|||Try:

sqlPar = new SqlParameter("@.parent_id", DBNull.Value)|||Perfect, it works, but now I have another problem.
I get this error:
This SqlTransaction has completed; it is no longer usable.

When I run Commit or Rollback code.|||Are you committing the transaction twice accidentally?|||No, I'm sure.
The only "strange" thing I do it's to call 2 different functions in my class to begin and commit/rollback transaction.|||Then you will have to show some code...|||'CConn is my class
CConn.BeginTransaction()

Dim arParameters as new ArrayList()

Dim sqlParOutput = new SqlParameter("@.id", SqlDbType.Int)
sqlParOutput.Direction = ParameterDirection.Output
arParameters.Add(sqlParOutput)

Dim sqlPar = new SqlParameter("@.parent_id", DBNull.Value)
arParameters.Add(sqlPar)

objTransaction = CConn.ExecuteNonQuery("sp", arParameters, false)

if objTransaction is nothing then objTransaction = CConn.ExecuteNonQuery("...")

if objTransaction is nothing then
CConn.CommitTransaction()
else
CConn.RollbackTransaction()
end if

The Begin, Commit and Rollback functions in CConn class simply call the same functions of SqlConnection object.
The ExecuteNonQuery function override standard function.|||This helps sort of not at all. We do not know what your class is doing. Is the return from CConn.ExecuteNonQuery a transaction object? What is the significance of objTransaction being nothing?|||Sorry, you're right.
Here the class methods:

 Public function BeginTransaction() as SqlTransaction
 Me.Conn = New SqlConnection(Me.sConnStr)
 Me.Conn.Open()
 'Start a local transaction
 Me.myTransaction = Conn.BeginTransaction()
 end function
 Public sub CommitTransaction()
 Me.myTransaction.Commit()
 Me.Conn.Close()
 end sub
 Public function RollbackTransaction() 'transaction as SqlTransaction)
 Me.myTransaction.Rollback()
 Me.Conn.Close()
 end function
 Public function ExecuteNonQuery(ByVal SQL As String, optional sqlParameters as ArrayList = nothing, optional toClose as boolean = true) as object
 Dim objReturn as object
 if Me.Conn is nothing then
 Me.Conn = New SqlConnection(Me.sConnStr)
 Me.Conn.Open()
 else
 if Me.Conn.State <> ConnectionState.Open then Me.Conn.Open()
 end if
 Dim sqlCmd As New SqlCommand(SQL, Me.Conn)
 'Must assign transaction object to Command object for a pending local transaction
 if not Me.myTransaction is nothing then sqlCmd.Transaction = Me.myTransaction
 Try
 if not sqlParameters is nothing then
 sqlCmd.CommandType = CommandType.StoredProcedure
 Dim sqlPar as SqlParameter
 for each sqlPar in sqlParameters
 sqlCmd.Parameters.Add(sqlPar)
 next
 else
 sqlCmd.CommandType = CommandType.Text
 end if
 sqlCmd.ExecuteNonQuery()
 Catch e As Exception
 objReturn = e
 End Try
 'must be clean up?
 if toClose then
 Me.Conn.Close()
 sqlCmd.Dispose()
 Me.Conn.Dispose()
 end if
 return objReturn
 End function