>Hi,
>I have an assembly 1. (contains textbox object (controllib) This assembly has reference to assembly 2. (contains class with shared member) and assembly 3 - (contains user form)
>
>Assembly 1 - has reference to assembly 2 and call shared function of class in assembly 2
>
>Then.. I begin to work with assebly 3 - Put textbox from toolbox on container.. try to change property - then error message happens -
>
>Method not found 'System.String ... and the name of my method
>
>but the method exist.. and if I start by F5 to debug - all works perfect!
>
>What it coud be?

I don't see how external references to assembly 3 are relevant. You're working on assembly 3 when the error occurs, right ?
Is this ASP.NET or WinForms?
Does this happen regardless of what property you attempt to change?
A complete guess but this is more likely to be a .NET versioning, missing DLL (or DLL reference in the assembly) problem than one with your code per se......