python is doing strange(once again)

for a add-on i work on, i need buttons with some python commands, for instance

well that works all fine in a script, but:
row = layout.row(align = True)
row.operator(‘select_inverse()’ , text = ‘select inverse’)

results in a grey line with the operator where the button should be. i had this before, but can’t find the solution anymore…

row.operator(“cloud.generate_cloud”, text=“DeGenerate”) (copied from the clouds addon) does work, also in mine
why chanching it to another validate operator gives this grey text

oh well, that was simple, but not too obvious.

'object.select_inverse()'is not working , ‘object.select_inverse’ is…

problem when the parentheseys(?) are needed, the button doesn’t appear then, back to writing a class for every button…