values.completed is set /onexptend
/ preinstructions = (intro1, intro2)
/ postinstructions = (end)
/ blocks = [1=DPDT; 2=payoff]
/onexptend = [values.completed = 1]
If it is zero, it would suggest that the procedure was terminated prematurely by the participant (e.g. by killing the script via the task manager). The participant's raw (trial-by-trial) data file might provide some pointers as to what happened when; without any additional information I cannot tell what happened, particularly if it's the only data set showing this anomaly.