flexural vibration beam+ponctual mass

Hello everyone,

I  modelled  a slender beam (an Euler-Bernoulli beam)  in flexural vibration in Abaqus  in order to do a natrural frequencies extraction. And, then i wanned to analyse the impact of a concentrated mass in its end. but for the first mode, i obtained a result understandable but not for the following modes which i verified analytically. the viewport of this fundamental mode can be found as a file attachement.

Could you please give me an explanation. And Thank you very much for your help