Hello, Can anyone please help me with this problem: I'm trying to make my first mod and at one point I need to add my custom filter in the editor. I'm trying it like this: grayed_part_filter = new EditorPartListFilter("myUnpurchasedParts", new Func<AvailablePart, bool>(myPartAvailable), string.Empty); EditorPartList.Instance.GreyoutFilters.AddFilter(grayed_part_filter); It's compiling all right, but when my plugin starting with this code, I'm getting an error: TypeLoadException: Could not load type 'System.Func`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'. I've looked all over the Internets already, everybody say that this is a .NET version mismatch error, and that it occurs at compile time. But I don't get any errors when I compile plugin! I get it only at the execution time. I've tried many variants already and out of versions what can be wrong. Maybe someone stumbled already on the similar error and know what could be causing it? Please help.