Can the series without update field be used as sourc series in rolling profile

I would like to archive forecast generated weeks ago. For example, the forecast generated 2 weeks ago is in Demantra series fore_minus_2.  This series does not have update field so it is not stored in the column of sales_data table. Its server expression is sum(#FORE@2@1#*1*#UNIT#). I created another series week2_fcst with updated  field of week2_fcst in sales_data table. Then I created a rolling profile with source series of fore_minus_2 and target series of week2_fcst. The rolling profile can be executed successfully but there is no data copied into week2_fcst. I checked Demantra implementation guide, The guide only states that target series must have an updated field but did not mention the same about source series. May I know whether a series without update field can be used as source series in rolling profile? If it can, why does not this rolling profile copy the