The WebView in older versions of Android did not fully support the HTML frame element.
I'd guess your calendar is displayed in a frame.
This forum uses frames to display code blocks in forum posts, if you load a forum page into a WebView on older versions of Android (2.? such as Froyo and Gingerbread) you'll see a long code block (in a frame) is not scrollable.
The same page will display properly using a WebView in ICS and the code block will scroll as expected.
Try it yourself, load
this recent non-related post of mine in your WebView and run your project on different Android versions.
There is no fix and no workaround that i know of.
Martin.