One of the most irritating issues that I encountered while working with XPages, especially when enhancing an existing Lotus Notes application is 'getComponent()' is null error.
My suggestion here will be silly, but I honeslty feel that there will be people out there who will acknowledge its severity
when a code fragement say, getComponent("fieldName").getValue() returns this error,
1.Check if a component with if "fieldName" actually exists
2. Note that "FieldName" is different from "fieldName" - cross check with the cases in the component name and the one mentioned in your code
Thanks and Regards,