[SSIS] Excel reference removed or disappears

Hi All

I am hoping someone can help me as I am stumbled by this problem 

I am using BiDs 2008 on WIN 7 (x64) with Office 2010 installed 

when I reference the Excel Interop Assembly through a script task it will add and reference correctly,

However when I save and close the script task, run it , then go back in to edit.. the reference is missing??

I then have to manually add it again..

Questions:

1. Is this a known problem and is there a solution?

2. Is it possible to Automatically add a reference within a SCript task without adding it manually? (possible solution)

Thanks

I have solved the problem 

Procedure:

Open .Net console (start> Visual Studio>Visual Studio Tools)

Added/Registered DLL Signature  (sn -Vr <file.dll>)

Added DLL to the GAC (gacutil/i <Fullpath and file reference to DLL>)