System.Security.Permissions.SecurityPermission

when i add in web.config

<system.data>
    <DbProviderFactories>
      <remove invariant="MySql.Data.MySqlClient" />
      <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.9.6.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" />
    </DbProviderFactories>
  </system.data>

my applications gives error

[SecurityException: System.Security.Permissions.SecurityPermission]
MySql.Data.MySqlClient.MySqlClientFactory..cctor() +26

trust level is restricted to medium by the host