How to enable MultipleActiveResultSets

Add MultipleActiveResultSets=True to your connection string

You can change your web.config, the connection string like this:

<add name="cn" connectionString="Data Source=PC\SQLEXPRESS;Initial Catalog=myDb;Integrated Security=True;MultipleActiveResultSets=True;" providerName="System.Data.SqlClient" />

This will allow multiple queries to be executed and their results processed concurrently on the same connection.