>character type,

hmmm.....
Is is hh:mm:ss?
My only idea is to define a report variable nTime with Value to store:

VAL(left(ctime, 2))*3600 + VAL(SUBSTR(ctime, 4, 2))*60 + VAL(SUBSTR(ctime, 7, 2))

Initial value 0, Reset at - End of Page and Calculate - Sum

and of course - convert it back to time format in the report field expression.

HTH