generalized geometric programming solver (GPPLAB)

My generalized geometric programming solver (GPPLAB) can not standarize an objective function of the form (posynomial function/ monomial function) and keeps giving the error

Error using sym/eval

Too many input arguments.

Error in gpproblem>standardize (line 318)

obj = eval( obj, {'' []} );

but if I enter the objective function in its generalized posynomial form it accepts it.

Is any thing wrong with z/w if z is a symbolic posynomial function and w is a symbolic monomial function?