Why is the calculated field not working in db connect?

[khmohammadzadeh]

I have defined a calculated field as eval(date_hour.".".date_minute.".".date_second) and I have mapped this filed to a db2 varchar column in db connect output, but this is not working and table's column that mapped to this field is not filled with the data, I have set the calculated filed's permissions to all apps and everyone, can anyone help me?
Thanks

[richgalloway]

Not all events have the date_* fields. Consider using strftime(_time, "%H.%M.%S") as an alternative.

[khmohammadzadeh]

We have date_* fields, but I have used suggested alternative and it is not still working.