Why do I get an error when pasting predictions from Predictive Planning?

Summary:

Cannot paste predictions to a Forecast scenario.

Content (required):

I have a from showing level 0 accounts on the rows and 12 months of cells across. The form is NOT Read-only with level 0 members selected for all dimensions. When I tried to paste the predictions generated by the Predictive Planning module, it gave me an error says, "No data was pasted. Possible reasons include: the cells are read only, the columns are collapsed, or the paste range extends beyond the beginning or end of the form."

I have made sure that the form in NOT Read-Only, all 12 months are expanded, and the prediction only generated 12 months of predictions in alignment with what I have defined in the form.