Missing BAI file?

Full question: 
I copied the bam and bai file into a local folder but when I try to open them, I got an error message saying that it needed the bai file. The bai file was in the same folder. What am i doing wrong?
Answer: 

The bai file needs to have the extension .bam.bai, not just bai.

This will be fixed in a future release, but versions prior to 2170 may have problems with this.