Cannot get ads to display

I'm trying to get this module to work, but I can only get it to show the debugging text in the block, it doesn't show ads.

Here is some information on my configuration:

1) I enabled the following modules:
* Adsense core
* Adsense Click Tracking
* Managed ads

2) I entered my publisher key at admin/settings/adsense/publisher. I got this key from my adsense account at google.com/adsense

3) "Enable AdSense click tracking?" is checked at admin/settings/adsense/click

4) At admin/settings/adsense I checked the following boxes (and only the following boxes):
* Enable test mode?
* Placeholder when ads are disabled?
* Enable AdSense section targeting?

5) I configured one of the managed blocks with the following:
* Block description: Adsense block 1
* Ad format: 180x150
* Ad slot ID: 499XXXXXXX
* Ad alignment left

While I am seeing the block, it is only showing debug information:
* client = pub-681578962*******
* slot = 499XXXXXXX
* Width = 180
* Height = 150

I'm not too sure what I should do to debug this. Can someone please give me some assistance?

Thank you.