Question: Maple not evaluating symbolic variables?

Dear Maple users,

I have very interesting problem with evaluating of only symbolic equations.

The problem is: (In document mode)
When I try to evaluate all numeric values for example typing 1+2 and press Enter it successfuly evaluates 3.
But when I try to evaluate symbolic values for example x + y nothing happens.

I tried lots of things to solve this, but no luck.
Shortly if the equation contains only numbers it evaluates successfuly.
And if the equation contains one or more symbolic variables like (x, y, z, variable1, test1), it does nothing.

What could be the problem?
 

(Because of this problem I cannot use the document mode, so I'm using the worksheet mode. Worksheet mode works good, but sometimes it is not calculating like document mode)

System is Windows 7 x64
Maple 2016
8 x 3.50GHz Xeon CPU
128 GB RAM
Windows Language is Turkish, (I tried with also USA English, but no luck either)
Keyboard is Turkish TR, (I tried with also US English, but no luck either)