Sweeping Multiple Parameters in ICAPS/4

I am trying to model a circuit where multiple components are modified
by a swept parameter.
(Note the script elements given below are example only and are not
meant to be true Spice list entries)

For example, A battery pack could be modelled by a voltage source and
series resistance modified according to the number of cells in the
pack:

Vbatt 0 1 DC={Numcells*1.5}
Rbatt 1 2 {Numcells*10m}
Rload 2 0 1k

Whenever I try an implement a sweep analysis entering a calculation in
the outer parameter of the component I get errors whenever the
parameter being swept is modified.
e.g.
Vbatt 0 1 DC={Numcells}
Rbatt 1 2 {Numcells*10m/1.5}
Rload 2 0 1k

passes the Vbatt parameter but kicks out on the Rbatt parameter.

I'm sure I've done this sort of thing before in ORCAD and it seems a
fundamental analysis requirement.

Can anybody help?