problem with importing mp4 in premiere

Hello there,
I have some clips recorded with different cameras like Z7, X3 and…
these files are in mp4 and m2t.
I couldn’t import these files in premiere pro cs6 in windows but I can import other file formats.
Interesting thing for me is I can import mp4 files which are recorded with cannon 5D without any problem!
my questions are:
1. Is my premiere working wrong or it’s how it works?
2. Is there any way I can import these files without conversion?

thank you

via Video Editing Forums: Digital Director – Adobe Premiere, Premiere Elements, and After Effects