Personally, I would use an expression to add the hyphen in then. Assuming your field name is of (n)varchar type, and is always 10 characters in it's original form:=LEFT(Fields!Matter_Number.Value, 6) & "-" & RIGHT(Fields!Matter_Number.Value,4)
Thom~
Excuse my typos and sometimes awful grammar. My fingers work faster than my brain does.
Larnu.uk