2.0: Attributten 'RequiresUniqueEmail' kunne ikke genkendes

Hej

jeg er ved at implementere sikkerhedsfunktionerne på mit website, men får følgende fejl når jeg går ind i asp.net configurations værktøjet under sikkerhed:

[Attributten 'RequiresUniqueEmail' kunne ikke genkendes]

min web.config ser ud som følgende:

<?xml version="1.0"?>
<configuration>
    <configSections>
        <sectionGroup name="microsoft.web" type="Microsoft.Web.Configuration.MicrosoftWebSectionGroup">
            <section name="converters" type="Microsoft.Web.Configuration.ConvertersSection" requirePermission="false"/>
            <section name="webServices" type="Microsoft.Web.Configuration.WebServicesSection" requirePermission="false"/>
            <section name="authenticationService" type="Microsoft.Web.Configuration.AuthenticationServiceSection" requirePermission="false"/>
            <section name="profileService" type="Microsoft.Web.Configuration.ProfileServiceSection" requirePermission="false"/>
        </sectionGroup>
    </configSections>
    <microsoft.web>
        <converters>
            <add type="Microsoft.Web.Script.Serialization.Converters.DataSetConverter"/>
            <add type="Microsoft.Web.Script.Serialization.Converters.DataRowConverter"/>
            <add type="Microsoft.Web.Script.Serialization.Converters.DataTableConverter"/>
        </converters>
        <webServices enableBrowserAccess="true"/>
    </microsoft.web>
    <appSettings/>
    <connectionStrings>
        <add name="StandardConn" connectionString="Data Source=******,1433;Initial Catalog=******;User ID=******; Password=******; Network Library=DBMSSOCN" providerName="System.Data.SqlClient"/>
    </connectionStrings>


  <location path="Admin">
    <system.web>
      <authorization>
        <allow roles="Admin" />
        <deny users="*" />
      </authorization>
    </system.web>
  </location>
 
  <system.web>
    <authentication mode="Forms">
      <forms loginUrl="~\login.aspx" defaultUrl="~\default.aspx" protection="All" timeout="30" />
    </authentication>
    <roleManager defaultProvider="SqlRoleProvider" enabled="true" >
      <providers>
        <clear/>
        <add name="SqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="StandardConn" />
      </providers>
    </roleManager>
    <membership defaultProvider="SqlMemberProvider">
      <providers>
        <clear/>
        <add connectionStringName="StandardConn" name="SqlMemberProvider" type="System.Web.Security.SqlMembershipProvider"
          enablePasswordRetrieval="false"
          enablePasswordReset="true"
          requiresQuestionAndAnswer="false"
          RequiresUniqueEmail="true"
          minRequiredNonAlphanumericCharacters="0"
          minRequiredPasswordLength="7"
          passwordFormat="Hashed"/>
      </providers>
    </membership>

    <pages theme="standard">
            <controls>
                <add namespace="Microsoft.Web.UI" assembly="Microsoft.Web.Atlas" tagPrefix="atlas"/>
                <add namespace="Microsoft.Web.UI.Controls" assembly="Microsoft.Web.Atlas" tagPrefix="atlas"/>
            </controls>
            <namespaces>
                <clear/>
                <add namespace="System"/>
                <add namespace="System.Collections"/>
                <add namespace="System.Collections.Specialized"/>
                <add namespace="System.Configuration"/>
                <add namespace="System.Text"/>
                <add namespace="System.Text.RegularExpressions"/>
                <add namespace="System.Web"/>
                <add namespace="System.Web.Caching"/>
                <add namespace="System.Web.SessionState"/>
                <add namespace="System.Web.Security"/>
                <add namespace="System.Web.Profile"/>
                <add namespace="System.Web.UI"/>
                <add namespace="System.Web.UI.WebControls"/>
                <add namespace="System.Web.UI.WebControls.WebParts"/>
                <add namespace="System.Web.UI.HtmlControls"/>
            </namespaces>
        </pages>
        <compilation debug="true">
            <buildProviders>
                <add extension=".asbx" type="Microsoft.Web.Services.BridgeBuildProvider"/>
            </buildProviders>
        </compilation>
        <httpHandlers>
            <remove verb="*" path="*.asmx"/>
            <add verb="*" path="*.asmx" type="Microsoft.Web.Services.ScriptHandlerFactory" validate="false"/>
            <add verb="*" path="atlasbatchcall.axd" type="Microsoft.Web.Services.MultiRequestHandler" validate="false"/>
            <add verb="*" path="atlasglob.axd" type="Microsoft.Web.Globalization.GlobalizationHandler" validate="false"/>
            <add verb="*" path="*.asbx" type="Microsoft.Web.Services.ScriptHandlerFactory" validate="false"/>
        </httpHandlers>
        <httpModules>
            <add name="ScriptModule" type="Microsoft.Web.Services.ScriptModule"/>
            <add name="BridgeModule" type="Microsoft.Web.Services.BridgeModule"/>
            <add name="WebResourceCompression" type="Microsoft.Web.Services.WebResourceCompressionModule"/>
        </httpModules>
    </system.web>
</configuration>