ODP.NET

I am wondering why this code:

**************************************************************************
Dim builder As New Oracle.DataAccess.Client.OracleConnectionStringBuilder
builder.DataSource = "datasourcename"
builder.UserID = "user"
builder.Password = "pass"

Dim oraConn As Oracle.DataAccess.Client.OracleConnection = New Oracle.DataAccess.Client.OracleConnection(builder.ConnectionString)

Dim oraCMD As New Oracle.DataAccess.Client.OracleCommand("SELECT field1, field2 FROM table", oraConn)

Dim MyDA As New Oracle.DataAccess.Client.OracleDataAdapter(oraCMD)

Dim ds As New DataSet

MyDA.Fill(ds)
DataGrid1.DataSource = ds.Tables(0)
**************************************************************************

throws a "Object reference not set to an instance of an object." at the line "MyDA.Fill(ds)"

and this code runs fine:

**************************************************************************
Dim builder As New System.Data.OracleClient.OracleConnectionStringBuilder
builder.DataSource = "datasourcename"
builder.UserID = "user"
builder.Password = "pass"

Dim oraConn As System.Data.OracleClient.OracleConnection = New System.Data.OracleClient.OracleConnection(builder.ConnectionString)

Dim oraCMD As New System.Data.OracleClient.OracleCommand("SELECT field1, field2 FROM table", oraConn)

Dim MyDA As New System.Data.OracleClient.OracleDataAdapter(oraCMD)

Dim ds As New DataSet

MyDA.Fill(ds)
DataGrid1.DataSource = ds.Tables(0)
**************************************************************************

Any thoughts?