SB-Prime variable intellisense

[AbsoluteBeginner]

Just in case, I will write in more detail my steps for post 8.

I launch SB-Prime.
I type the text “a = 3” and click “Enter”.
I type the text “test = 5” and click “Enter”.
Now I position the cursor at the end of the first line and click "Enter".
I type the text "b = 4". Then I click with the mouse at the beginning of the empty fourth line and type the text.
I write the letter “a” and this letter is displayed in the list.
Next, I write “+ b”, but the list does not appear. It turns out as seen in the screenshot. 
( But, I have a string "a + b" with spaces.)