What do you see in debugging ? Is the table filled with data ?
Does v_string get filled in the loop ?
Does v_string get split in the different workarea fields ?
Also how come that both ta_csv and ta_csv_data are defined as zst_preisupload ? What is the definition of this structure ? If they are the same then where is the comma coming from ?
I presume that table ta_csv_data should be a string table and not of type zst_preisupload.