I am trying to replace all the occurrences of two spaces between a period and the start of the next sentence into one space. I looked around and in theory, in the Find and Replace dialog and using the "Find What" field, enter a space and then {2,}
Then I want to put one space in the field of what to replace this with. Somehow I haven't gotten this correct because the find command does nothing.

How can I accomplish this? Thanks.