sqlException was unhandled invalid object name "unc_tb"

Imports System.Data
Imports System.Data.SqlClient
Public Class Form1
Dim cn As SqlConnection
Dim ds As DataSet
Dim da As SqlDataAdapter
Dim r As DataRow
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim strconnection As String = "data source=.\SqlExpress;initial catalog=master;integrated security=true"
cn = New SqlConnection(strconnection)
cn.Open()
Try
cn.ChangeDatabase("dd_db")
Catch ex As Exception
Try
Dim command As New SqlClient.SqlCommand("create database dd_db", cn)
command.ExecuteNonQuery()
command.Connection.ChangeDatabase("dd_db")
Dim command1 As New SqlClient.SqlCommand("create table dd_tb ([admi.num][int](10),[tran.num][int](4),[name][char](40),[age.reci][int](2),[sex.reci][char](8),[or.kid.d][char](22),[specify][char](50),[consang][char](20),[rec.b.g][char](8),[r_iggt][char](8),[r_iggr][char](12),[r_igmt][char](8),[r_igmr][char](12),[r_hcvt][char](8),[r_hcvr][char](12),[r_pcrt][char](8),[r_pcrr][char](12),[r_hbvt][char](8),[r_hbvr][char](12),[r_bpcrt][char](8),[r_bpcrr][char](12),[blood.gp][char](10),[rhla_aa][int](8),[rhla_ab][int](8),[rhla_ba][int](8),[rhla_bb][int](8),[rdr_a][int](8),[rdr_b][int](8),[prior.bl][char](8),[type.blo][char](15),[number.o][char](15),[num.bl.t][int](2),[datel.bl][date](10),[erythrop][char](8),[hypr_pre][char](8),[rec_schi][char](8),dia_rec][char](22),[sit_urn][char](12),[dial_pre][char](8),[dia_typ][char](20))", cn)
command1.ExecuteNonQuery()
Catch ex1 As Exception
MsgBox(ex.Message)
End Try
End Try
da = New SqlDataAdapter("select * from dd_tb", cn)
Dim x As New SqlCommandBuilder(da)
ds = New DataSet()
da.Fill(ds, "dd_tb")
End Sub
End Class

This is the code at the line of da.Fill(ds, "dd_tb") after compile it brings this message sqlException was unhandled invalid object name "unc_dd" I tried unc_dd.dbo.unc_dd but it brings the same message
So can you help me to find the solution
Thanks in advance
Dalia

I also tried da.Fill(da) but the same message appear
so I remove this line the form appear But at button new to add new to the database it brings this message nullReferenceException was unhandled object reference not set to an instance of an object