Getting this error continuosly:Object cannot be cast from DBNull to other types.

[denmarkstan]

Please great people help me look into this from scratch.

i have field definition like this:

Column Name Data Type
StaffID nvarchar(20)
Title Varchar(20)
FirstName varchar(50)
SecondName varchar(50)
Gender nvarcher(20)
ClassTeaching nvarcher(20)
PhoneNumber nvarcher(50)
Level nvercher(20)
Salary money
Passport image

Here is vb code below, and when i run it i get the error on the title of this thread:

Dim connection As SqlConnection = Nothing
        'Try
        Dim img As FileUpload = CType(imgUpload, FileUpload)
        Dim imgByte As Byte() = Nothing
        If img.HasFile AndAlso Not img.PostedFile Is Nothing Then
            'To create a PostedFile
            Dim File As HttpPostedFile = imgUpload.PostedFile
            'Create byte Array with file len
            imgByte = New Byte(File.ContentLength - 1) {}
            'force the control to load data in array
            File.InputStream.Read(imgByte, 0, File.ContentLength)
        End If
        ' Insert the employee name and image into db
        Dim conn As String = ConfigurationManager.ConnectionStrings("localConnectionString").ConnectionString
        connection = New SqlConnection(conn)

        connection.Open()
        Dim sql As String = "INSERT INTO StaffData(StaffID,Title,FirstName,SecondName,Gender,ClassTeaching,PhoneNumber,TeachingLevel,Salary,Passport) VALUES(@StaffID,@Title,@FirstName,@SecondName,@Gender,@ClassTeaching,@PhoneNumber,@TeachingLevel,@Salary,@Passport) SELECT @@IDENTITY"
        Dim cmd As SqlCommand = New SqlCommand(sql, connection)
        cmd.Parameters.AddWithValue("@StaffID", txtStaffID.Text.Trim())
        cmd.Parameters.AddWithValue("@Title", txtTitle.Text.Trim())
        cmd.Parameters.AddWithValue("@FirstName", txtFirstName.Text.Trim())
        cmd.Parameters.AddWithValue("@SecondName", txtSecondName.Text.Trim())
        cmd.Parameters.AddWithValue("@Gender", txtGender.Text.Trim())
        cmd.Parameters.AddWithValue("@ClassTeaching", txtClassTeaching.Text.Trim())
        cmd.Parameters.AddWithValue("@PhoneNumber", txtPhoneNumber.Text.Trim())
        cmd.Parameters.AddWithValue("@TeachingLevel", txtTeachingLevel.Text.Trim())
        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim())
        cmd.Parameters.AddWithValue("@Passport", imgByte)
        Dim id As Integer = Convert.ToInt32(cmd.ExecuteScalar())
        Image1.ImageUrl = "~/ShowImage.ashx?id=" + id
        lblResult.Text = String.Format("Employee ID is {0}", id)
        'Catch
        '    lblResult.Text = "There was an error"
        'Finally
        connection.Close()
        'End Try
    End Sub