First
- Via SA38 execute report BALVBUFDEL (refresh ALV buffers)
- Perform The Consistency Check, is the actual catalog consitent with your expectations?
Then read Generating the Field Catalog Manually, and fill INTTYPE or give ddic reference.
Hint: Also switch to OO ALV cl_gui_alv_grid (21st century) or at least use REUSE_ALV_GRID_DISPLAY_LVC.
Regards,
Raymond