Third, five most important factors of information system successfulness pointed out by information system managers are almost identical with the ranking of the most important factors of information system successfulness according to information technologies specialists, users and user managers. The main difference lays in the factor of capabilities of the top management. Users see it as the most important factor for information system successfulness, while managers think of it as moderately important. Consequently, top management must show enthusiasm and support to information technologies specialists, how they would use possibilities of information system for their managerial process. Only trough that effort can the user be encouraged to use more functions of information system. This could, in return, increase the application of information system in their everyday work and improve possibilities for success of information system.