好吧，我想出来了。

我的$ cityName变量是：

My $cityName variable was this:

$cityName = "Monterrey, NL";

逗号和NL之间的空格。我使用str_replace为+更改，并获得有效的网址，如文档中所示：

The white space between the comma and "NL". I used str_replace to change " " for "+" and get a valid url like in the documentation:

http://code.google.com/intl/es/apis/maps/documentation/geocoding/

问候，非常感谢您的帮助！

Greetings and thanks a lot for your help!