Question

I have been assigned a new project to do some enhancements, but while compiling the given solution I am facing this error:

Unknown server tag 'dxtc:ASPxTabControl'

The solution is using devExpress Libraries Version 11. I have never ever worked with DevExpress and dont really have an idea what this error is. Could any one please help me?
Here is my code below:

<dxtc:ASPxTabControl ID="tabMaster" runat="server" ActiveTabIndex="3" CssFilePath="~/App_Themes/Glass/{0}/styles.css"
        CssPostfix="Glass" TabSpacing="0px">
        <Tabs>
            <dxtc:Tab Text="Calibrations">
            </dxtc:Tab>
            <dxtc:Tab Text="Custom Assemblies">
            </dxtc:Tab>
            <dxtc:Tab Text="Panel Orders">
            </dxtc:Tab>
            <dxtc:Tab Text="Will Call">
            </dxtc:Tab>
        </Tabs>
        <Paddings PaddingLeft="0px" />
        <TabStyle HorizontalAlign="Center" Width="55px">
        </TabStyle>
        <ContentStyle>
            <BorderTop BorderStyle="None" />
        </ContentStyle>
    </dxtc:ASPxTabControl>

Answer 1

You need to register the dx control in the .aspx markup

<%@ Register assembly="DevExpress.Web.v8.3, Version=8.3.2.0, Culture=neutral, 
    PublicKeyToken=b88d1754d700e49a" namespace="DevExpress.Web.ASPxTabControl"
    tagprefix="dxtc" %>

(documentation)

or in the web.config

 <system.web>
    <pages>
      <controls>
        <add tagPrefix="dxtc" assembly="DevExpress.Web.v10.2" namespace="DevExpress.Web.ASPxTabControl" />
      </controls>
    </pages>

Don’t forget to adjust the assembly name to the version you are using.