Are you using Pro?
I found this in the help section:
The suggested procedure for entering driver parameters is following (check first that "Auto calculate unknowns" option is checked):
1. Enter
Mms and
Cms
This gives
fs. If either is not available, then enter
fs and other parameter.
2. Enter
Sd,
Bl and
Re
Now, you should get all but
Qms (and
Qts),
Vas. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See
FAQ.
3. Enter
Rms or
Qms.
Either one will do, although I tend to prefer
Qms over
Rms, because it can usually be measured in driver measurement procedures.
4. Enter
Hc,
Hg and
Pe.
If
Hc or
Hg or either is available, then enter
Xmax and optionally either
Hc or
Hg if available.
5. Enter number of voicecoils.
This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though.
6. Correct
Znom, if necessary.