The scaling selection using SHIFT doesn't seem to be working for me all of a sudden.......how can I resolve ?

The scaling selection using SHIFT doesn't seem to be working for me all of a sudden.......how can I resolve ?

Specifically, when I select and object I used to be able to hold SHIFT while re-sizing the object and keeping it in scale.

All of a sudden, I don't have that option as my SHIFT key doesn't seem to activate within AI

B.Marks