Deploy VSTO Document solution to Excel 2003

We've followed several how-to's from the internet to no avail, including: http://msdn.microsoft.com/en-us/library/bb332051.aspx#8

We have a suspicion that there is a security problem as the first line of our code is a logging message and this is not being hit.

No error message is given by excel, the spreadsheet opens and is usable but there is no access to any code and all buttons are disabled.

Any help would be massively appreciated as we've spent many hours trying to figure this out!

Thanks

***************EDIT******************************

Here's the actual cause of 开发者_StackOverflow社区the problem from my IT Dept:

...was caused by the Organisational Unit container they were held in being 
deleted. This was restored and group memberships and distribution lists access
for individual accounts were then added manually

Turns out the problem was that over the weekend IT had downgraded all our versions of Excel from Professional to Standard. Not all VSTO works in Excel Standard, but it doesn't tell you this, it just doesn't work.

After upgrading we're all happy again!

Cheers