Export settings the same but some videos play and others don't.

Output:     C:\users\sinc\Desktop\vids\metro4_1.mp4

                1920x1080, 29.97 fps, Progressive

               VBR, 1 pass, Target 32.mbs, Max 40.00 Mbps

                AAC, 192 kbps, 48 kHz, Stereo

Source:      Sequence, Metro4

                 1440x1080 (1.3333), 29.7 fps, Progressive, 00;35;20;12

                  48000 Hz, Stereo

I know that the aspect ratio is off but it has never been a problem. (may be it is and its just picky) But, i do all my videos like this and some are completely playable and uploadable to Youtube. Others finish exporting and some appear with a movie icon saying mp4 size: 24 bytes. After clicking on it, it says: Windows Media Player encountered a problem while playing the file.

May be a missing codec? Doesnt make sense if one video will play and another doesnt with same settings.