>Ok, this worked... why do I need the ( ) and when should I use them? I thought the & was what I needed

If the command is likely to have an embedded space, as is common nowadays, then you'd have to make the entire command a macro expansion. Otherwise an embedded space in the character string is going to cause the error you saw. A named expression in this case won't have the problem.

HTH.

p.s. The Hackers' Guide (www.hentzenwerke.com) has a good discussion of this issue.