Irregular operation of Bind [4.27]

Hello,
I have problem with binding dispatcher to event. In most of cases it works okey, but sometimes ( I cannot find any reason why ) code behaves like bind was never done.

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When it dont work, dispatcher is called as it should be but event is never trigered.

Could someone is there any time when bind wouldnt work ?
Or give me some hint how to resolve this problem.

Thank you in advance for your help

ss