Dynamic graph turning static

I'm having trouble with a graph I'm trying to make dynamic.

I made a named value "bottomright" that returns a reference to the bottom
right cell of my data set. bottomright = OFFSET('Foo'!$B$2,
COUNTA('Foo'!$A:$A)-2, 3, 1, 1). That much works nicely.

The trouble I'm running into is in defining the data range for my graph. I
set the data range to ='Foo'!$B$1:bottomright, and it makes a nice graph
with exactly the data I want in it. When I add data, though, the graph
doesn't update. I go back and check the data range, and it has switched my
variable "bottomright" with a static reference to the cell it pointed to
when I initially set up the graph.

Is there some way to have the data range leave this dynamic? Thanks!


-Joey