Manually adjusting asp.net code gives parser error

I am trying to learn asp.net after creating a bunch of pages using asp 3.0. To do this I am using Visual Studio Express 2013 for web, dragging tables to create grid views, and then looking at the code in hopes of better understanding so I can eventually hand code.

So I use the gridview tasks > edit columns and change the item style to give a column a specific width. That works. I then go to the code and manually do the same thing for another column. When I run it in my browser I get this:

Server Error in '/portal2' Application.

Parser Error

Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.

Parser Error Message: System.Web.UI.WebControls.DataControlFieldCollection must have items of type 'System.Web.UI.WebControls.DataControlField'. 'ItemStyle' is of type 'System.Web.UI.HtmlControls.HtmlGenericControl'.

Source Error:


Line 29:                 <asp:BoundField DataField="assigned" HeaderText="Assigned To" SortExpression="assigned" />
Line 30:                 <asp:BoundField DataField="customer" HeaderText="Customer" SortExpression="customer" />
Line 31:                 <asp:BoundField DataField="jobno" HeaderText="Job No" SortExpression="jobno" /><ItemStyle Width="100px" /></asp:BoundField>
Line 32:                 <asp:BoundField DataField="duedate" HeaderText="Due Date" SortExpression="duedate" DataFormatString="{0:d}" ><ItemStyle Width="100px" /></asp:BoundField>
Line 33:                 <asp:BoundField DataField="issue" HeaderText="Issue" SortExpression="issue" />

Source File: /portal2/issues.aspx    Line: 31

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34237

This makes no sense. If I start using VS.net am I forced to use all the stupid little wizards and not hand code at all?