Customers Cannot Checkout

[mjb111]

I have been asked to take a partially-completed Prestashop website, finish it, and make it work within a few days. Categories have been created and products loaded, but customers cannot checkout their cart. It's set on the 5-step checkout process, and steps 1-3 are fine. When a customer is on the Addresses screen and clicks "Next," they go to a blank theme page, not to the Shipping page. The shipping configuration is the most likely culprit, but not having set it up myself and trying to learn the system, I can't find the problem. It is currently only configured for USPS and customer pick-up. Here are the things I've tried:

1. Turned on US Zone for 1st Class & Parcel, disabled all other USPS options – NG
2. Under Shipping tab > Countries, Zip Code Format required field was blank – filled in – NG
3. Changed Price Ranges for 1st Class & Parcel from $0.0000 to $0.01 – NG
4. Changed Weight Ranges for 1st Class & Parcel - NG
5. Tried change to Settings in problem reported in blog for Default Carrier setup – NG
6. In Preferences, changed from 5 Step to One Page checkout – really NG! Checkout disappeared completely

If anyone has any ideas, I'd sure apperciate it.

[tomerg3]

You should turn on error reporting (/config/config.inc.php line #29) and try it again, it should print an actual error.