QComboBox Signals doesn't invoke the called function

[ladiesfinger]

usually , i didn't give SLOT() parameter in python ( in c++ , i did give )

I've implemented a push button previously , connected it to a function processimg as:

self.connect(self.process,QtCore.SIGNAL('clicked()'),self.processimg)

self.connect(self.process,QtCore.SIGNAL('clicked()'),self.processimg)

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It worked superb ....

but this function doesn't get invoked .

proper function for event changing of a combobox ?