Microsoft.ReportViewer.Common -> Error in compilation WebSite

in an old ASP.NET WebForms solution I am having problems compiling it about the ReportViewer component. In particular I get the following build error:

Error
Could not load file or assembly 'Microsoft.ReportViewer.Common, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

In the web.config file I have these 2 rows:

    <buildProviders>
 <add extension=".rdlc" type="Microsoft.Reporting.RdlBuildProvider, Microsoft.ReportViewer.Common, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
</buildProviders>

<assemblies>
<add assembly="Microsoft.ReportViewer.Common, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
</assemblies>

How can I solve this problem?

Thanks a lot in advance.

Luis