Upgrade not going beyond 3.8.1
 

I downloaded the VB 3.8.3 files. Upload the install directory to my server. I then ran upgrade.php, completed steps 1-5, until I was returned to the admin cp.
However, it only upgraded to 3.8.1. I tried running upgrade.php again, but am still only getting to 3.8.1.
Any guidance would be appreciated.