I had a similar problem, you have to define extra types in the params files, for 
example I added

gp.type.a.size = 3
gp.type.a.1.name = boolean
gp.type.a.2.name = double

Then you need to add new node constraints to use the new types

gp.nc.7 = ec.gp.GPNodeConstraints
gp.nc.7.name = logical2c
gp.nc.7.returns = boolean
gp.nc.7.size = 2
gp.nc.7.child.0 = boolean
gp.nc.7.child.1 = boolean

have a look at ec/app/regression/noerc2.params too for a full example using the 
set types too