* If I many ask what is the major reason while some countries ruling class ban bitcoin transaction?
Because they have no control over bitcoin and it can also be used by some criminals on the black market or to do money laundering.
* What is the negative effects using crypto as currency?
I see no bad effects on using it except if it is banned on your country.
* what harm does bitcoin contributes a country that can lead to ban?
Like I said on your first questions, criminals can freely do any bad intentions using bitcoin leaving no trace. Their image or reputation to their people and to other countries won't be good if an issue spread about that incident. This could also result for other countries to ban bitcoin.