tf.zeros doesn't accept a tensor argument

ValueError: Shape must be rank 1 but is rank 0 for 'zeros_2' (op: 'Fill') with input shapes: [], [].

tensorflow/docs_src/programmers_guide/tensors.md

@@ -197,7 +197,7 @@ For example, here is how to make a vector of zeros with the same size as the
 number of columns in a given matrix:
 
 ``` python
-zeros = tf.zeros(tf.shape(my_matrix)[1])
+zeros = tf.zeros(my_matrix.shape[1])
 ```
 
 ### Changing the shape of a `tf.Tensor`