Customized Promotion task template gives error on selecting view

@Dear experts,

I have succesfully created a custom template form for promotion task. The form works fine but throws an error when I change the view option using the combobox. Please find the attached document for error and the code for jsp. The selection works fine, but the error is unexpected. Can you spot the error and give me some pointers to solve this problem?

Regards,

Gautham