MP3Gain weird result with a song

Hi everyone,

I use MP3Gain for some time now, I set it to 90 db and it has always worked well.

But I have a song setted at 90 db like the others and I have the feeling it sounds the same volume (but I can be wrong), but the waveform displayed in Traktor is completely different from the others:



On the left, a "normal" song (the waveform is thin but it's logic as I set my songs at 90 db). On the right, the song that still has a huge waveform after MP3Gain. According to the VU meter, it also sounds a bit louder but this could be due to the fact that the song has a constant loud bassline... Anyway, MP3Gain confirm the 90db volume, so it shouldn't sound louder nor look louder on the waveform, right ?

I also recorded a "set" containing little parts of different songs, and uploaded it on Soundcloud. I'll let you guess where the weird song is:



Does anyone have a clue about this? I really want to understand that behaviour. I'm pretty new in DJ stuff and I want to understand what I do and learn good practices as of now.

Thank you very much in advance!

JB