2.0: membership provider configuration

[RAM]

Hello,
I have to change password rules (minRequiredNonalphanumericCharacters="0").
According to information found in Internet I have updated web.config, but I
receive runtime error: The entry 'AspNetSqlMembershipProvider' has already
been added.
I enclose my web.config (I use Polish language). Before adding membership
section everything was OK.
I need you help, because I don't understand the problem - what's wrong.
Thank you!
/RAM/

<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
<appSettings>
<add key="Wersja" value="0.1"/>
<add key="DomyslnaBaza" value="MIMMagazynDemo"/>
<add key="BazaDemo" value="MIMMagazynDemo"/>
<add key="UzytkownikDemo" value="demo"/>
<add key="DomyslnaStawkaVAT" value="22%"/>
<add key="DomyslnaJednostkaMiary" value="szt"/>
<add key="IleMiesiecyWLogu" value="1"/>
</appSettings>
<connectionStrings>
<add name="MIMMagazynDemo"
connectionString="Data
Source=.\SQLEXPRESS;AttachDBFileName=|App_Data|MIMMagazynDemo.mdf;Integrated
Security=True"
providerName="System.Data.SqlClient" />
<add name="SqlServices"
connectionString="Data
Source=.\SQLEXPRESS;AttachDBFileName=|App_Data|aspnetdb.mdf;Integrated
Security=SSPI;User Instance=True"
providerName="System.Data.SqlClient" />
</connectionStrings>
<system.web>
<roleManager enabled="true" />
<compilation debug="true"/>
<authentication mode="Forms">
<forms name="MIMMagazyn" loginUrl="Logowanie.aspx" />
</authentication>
<authorization>
<deny users="?" />
</authorization>
<customErrors mode="RemoteOnly" defaultRedirect="Blad.html">
</customErrors>
<sessionState mode="InProc"
cookieless="false"
timeout="20"/>
<membership defaultProvider="AspNetSqlMembershipProvider">
<providers>
<add name="AspNetSqlMembershipProvider"
type="System.Web.Security.SqlMembershipProvider, System.Web,
Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
connectionStringName="SqlServices"
minRequiredPasswordLength="4"
minRequiredNonalphanumericCharacters="0" />
</providers>
</membership>
</system.web>
</configuration>

 

[RAM]

(By the way, AttachDBFileName=|App_Data| should be changed to
AttachDBFileName=|DataDirectory|...)