Unable to call a custom dll method in Microsoft SSRS

hi the community , as soon as I try to call a function from a simple custom DLL with expression on SSRS, I receive an error message : "System.Web.Services.Protocols.SoapException: The Value expression for the textrun 'Textbox2.Paragraphs[0].TextRuns[0]' contains an error: [BC30007] Reference required to assembly 'system.runtime, Version=6.0.0.0, Culture=neutral,".

My project targets .NET version 6 (netcore ) and my system works on net.standard 4.8,

I also add that the version of ssrs is that of 2019, the error message also appears with the 2022 version

I encounter this error message for any custom dll. I have followed various tutorials and the official documentation, but the problem persists. Thanks !