Maximize function for the volume of a box?

Questions
,
1

I’m trying to maximize the volume of a box with an open top using this:

Maximize[{x*y*z , 2 x*z + 2 y*z + x*y == 12}, {x, y, z}]

I know the answer should be this

{4, {x -> 2, y -> 2, z -> 1}}

But I get this as a result

{\[Infinity], {x -> Indeterminate, y -> Indeterminate, 
  z -> Indeterminate}}
2

In[1]:= Maximize[{xyz, 2 xz + 2 yz + x*y == 12, x >= 0, y >= 0,
z >= 0}, {x, y, z}]

Out[1]= {4, {x -> 2, y -> 2, z -> 1}}
3

Thank you very much!