I had a look at the thread - htmlb Browser Support
As Max mentioned in the thread, I specified the device as 'NN6' for 'Others'. However, the default IE5 files are still being used.
As I debugged I noticed that the browser id is "NN6" and so is the device, but finally when the BSP is displayed, sapUrMapi_ie5.js is used.
Any help regarding this would be greatly appreciated.