I'm a new Javascript user trying to put code into Acrobat forms. When I use the 'Simplified Field Notation' for calculations (e.g. gr1*r1+t1*tr1) the calculation is not performed. The 'Value is...' option does work, but my requirements are slightly more complex.
Why is this?

I don't think this is the place to ask about Javascript. Have you tried here?

http://p2p.wrox.com/book-asp-net-website-programming-problem-design-solution-23/5