UPS error on custom checkout

Hi,

I am using a custom check out module on my 1.5.1.3. If I enable UPS shipping module I am getting the following error. This error is thrown when I get a quote in Cart and click continue to check out. The checkout is a custom check out module with controller and tpl. I am not a php developer can anyone help me to understand what will be the issue here. Really appreciate your help.

PHP Notice: Undefined index: city in ...\catalog\model\shipping\ups.php on line 137
PHP Notice: Undefined index: zone_code in ...\catalog\model\shipping\ups.php on line 138