Error: Data type mismatch in criteria expression
<p>I've made a program about flights using C# linked to an Access DB (for school).<br>
However, after doing all the basics, I wanted to score some extra points.</p>

<p>My DB consists of two tables: <code>reizigers</code> (passengers) and <code>vluchten</code> (flights). All the classes and variables should be defined correctly.</p>

<p>My problem: I want to be able to <em>search</em> for flights <em>between</em> certain <em>cost</em> ranges.</p>

<p>However, after executing the query and thus trying it, it gives the error: </p>

<blockquote>
  <p>Additional information: Data type mismatch in criteria expression.  </p>
</blockquote>

<p>In my DB, the cost is <code>kost</code>, and it's just a single Integer (e.g., 240).</p>

<p>Does anybody have any idea what it might be?</p>

<p><img src="https://i.stack.imgur.com/MvvVd.png" alt="repository">
<img src="https://i.stack.imgur.com/3VPga.png" alt="wpf window, entry"></p>