SQL Server does not handle comparison of NText, Text, Xml, or Image data types

This error occurs when data binding a repeater: SQL Server does not handle comparison of NText, Text, Xml, or Image data types

protected void Page_Load(object sender, EventArgs e)
{
    topicid = Convert.ToInt32(Request.QueryString["topic".ToString()]);

    if (!IsPostBack)
    {
        MusicForumDataContext db = new MusicForumDataContext();

        var query = from p in db.posts
                    where p.categoryid == NAME
                    select p;
        rptposts.DataSource = query;
        rptposts.DataBind(); <---- ERROR
    }
}