Without knowing what Object Name actually is, or what your prompt is, I would think that your object resolves to a number but your prompt is returning char data.
We have faced samilar kind of issue with when we have converted desci reports in to webi reports.
One of the solution is append single quote to your prompt values in the table.
if table value is ABC convert it to ‘ABC’
Oracle cant understand the value type simply prompt retuturs alphbets with out quotes. without quotes it treats as number but actual value is character.
In deski it is not the case.