Halo 3 ODST Audio file missing?

[ODSTBlizzard]

I have gotten 28 audio files on halo 3 odst but I can't find the las. One hat you need for the 30th one. I have used a map but it doesn't appear to be there. Can someone please help?????
I have gotten almost all the audio files and have checked again and again with a map, but i can't find the second last one. Thats what i meant.

 

[Benjamin]

check out this web site it has locations and video of the audio file. You might have to go back and check locations again but this helps out a lot. http://nextgenwalkthroughs.com/Halo_3_ODST_Audio_Log_Locations