It doesn't work because you can't use a null character in the pattern - if you want to search for that the pattern needs to have "\00". I don't usually use this, so I don't know why this is like that. Read the help for more details.
In general, there are much better ways of sharing screenshots than taking a picture of the actual screen. The Code Capture Tool is very convenient for LV, but you can also use the printscreen key on your keyboard and Paint.
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