Custom Workflow Activity & Web.Config

Hi,

I'm using a custom activity and I want to read some parameters from config.

Any way I read the appSettings I can´t find de keys. I tried diferent ways:

System.Web.Configuration.WebConfigurationManager.AppSettings["LogFilePath"];              
System.Configuration.ConfigurationSettings.AppSettings["LogFilePath"];
System.Configuration.ConfigurationManager.AppSettings["LogFilePath"];

and the configuration exists on the FIM Portal web.config like this:

<configuration>
   <appSettings>
      <add key="LogFilePath" value="D:\temp2"/>
   </appSettings>
</configuration>

What can be happening??

Many thanks,

DD