Why I can't use theano.tensor.argmax and theano.tensor.mean correctly

I am learning Theano now but there are always some problems.my code is as follows:

import theano 
from numpy import *
import theano.tensor as T
a = [1,2,3,4]
b = [7,8,9,10]
print T.argmax(a)

I thought it would print the index of '4',but the result is:

argmax

what's more,when I am using T.neq().just as follows:

import theano 
from numpy import *
import theano.tensor as T
a = [1,2,3,4]
b = [7,8,9,10]
print T.neq(a,b)

the result shows:

Elemwise{neq,no_inplace}.0

I really new to this and have no idea,did I miss anything?thank you in advance..