Wrong number or type of arguments for overloaded function 'SX_get'

Hi,
In python code, my code cause following error:

NotImplementedError: Wrong number or type of arguments for overloaded function ‘SX_get’.
Possible prototypes are:
get(self,bool,Sparsity)
get(self,bool,Slice)
get(self,bool,IM)
get(self,bool,Slice,Slice)
get(self,bool,Slice,IM)
get(self,bool,IM,Slice)
get(self,bool,IM,IM)
You have: ‘(SX,bool,SX)’

There is my code:

import casadi as ca
N = 5
max_neig = 3
i = 1
j = 1
position = ca.SX.sym(“position”, 3 * N)
neighborIndex = ca.SX.zeros(N, max_neig)
a = position[3 * i]-position[3 * neighborIndex[i, j]]

Why do these errors occur? And how do I fix it?
Thanks a lot!