Find files which doesn't contains a text

[suwari]

Hi

I try to to find files in a folder, which doesn't contains a text (example "blabla")
I try to use the "RegEx 2" but I don't know what is the proper regex term is for "not contains"
Can You show an exampe?

[NotNull]

And enabling the Find files NOT containing the text checkbox in that same dialog window doesn't give you the expected results?