You first execute statement could be failing:

$sthGetOldBandwidth->execute($data[0]);
[download]

Put 'or die $sth->errstr()' after that one (like you have after the second one) and it might give you an idea of the problem. The second one probably isn't failing because you just have NULL returning from the first one (if I understand your code correctly).

Off the top of my head a possible problem, if this works from local machines but not on remote, the remote database may not be allowing connection from your machine, mysql databases tend to check for certain hosts as well as the username and password, depending on how the admin set them up.

Hope that helps
Chris