title: Operand type clash: nvarchar is incompatible with image
body: <p>I'm using a SQL Server 2008 stored procedure to create a new record with 
  this syntax:  </p>
  
  <pre><code>cmd.Parameters.Add("@photo", DBNull.Value)
  cmd.ExecuteNonQuery()
  </code></pre>
  
  <p>but the result is a: </p>
  
  <pre><code>Operand type clash: nvarchar is incompatible with image 
  </code></pre>
  
  <p>Photo is not the only parameter but is the only image one, I am not passing 
  a nvarchar but a null value, am I missing something?</p>