Empty or null elements within an xml fragment fail to convert when numeric or decimal format is used, eventhough such conversion goes without a problem In a normal select statment. However, I noticed that float works just fine. Why? I don't know. I used the following approach to this problem:

a) if precision and scale components of the number ( e.g. Decimal(19,10) ) are important then I make sure default of 0 is used in the xml fragment instead of empty or null.

b)If percision and scale arenot important then I use float in the select statemnt. In your case you used Numeric(20,0) to report just the integer part. Float will work fine.

Hope this helps.