Could not load file or assembly Microsoft.Practices.EnterpriseLibrary.Logging exception

C# 4.0, MS Practices Enterprise Library 5.0

I have used the Enterprise Library Configuration tool for creating a Logging Application Block and I have obtained a configuration file like this:

<section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />

<loggingConfiguration name="" tracingEnabled="true" defaultCategory="General">

                …

                …

</loggingConfiguration>

Unfortunately, I got the following exception while trying to use the Enterprise Library Logging Application Block:

“An error occurred creating the configuration section handler for validation: Could not load file or assembly 'Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.414.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)”

I solved this problem by setting to null the PublicKeyToken.

PublicKeyToken=null