M.

1. You never seem to listen! You're getting in a muddle with skip again when several people over the years have advised you to use scan.
2. Next, Sum takes you to the bottom of the file, and you don't return to where you were before (not storing the recno to GOTO). So you only get the one.
3. Even if it DID sum each set it means you're travelling through the table many times.
4. Assuming tot_t is a field in the table, why not tot it up as you go?
e.g.

Select curbilldata
SCAN
  m.divi =  curbilldata.divi
  m.r    = 0
  Scan Rest while m.divi = curbilldata.divi
    m.r = m.r + tot_t
  EndScan

* I don't know what you're doing with this next line
* Seems all the records in the range of the inner scan will get the same  tot_tot value
* and will ruin you file pointer. Reconsider.
* ___________________________________________
  replace tot_tot WITH m.r/2 for m.divi = curbilldata.divi
  
EndSCAN

Terry