You can't type into a field of type "Calculation". In order to allow typing, the field has to be either text, number, etc...
If you want the calc, but to allow override, you might want to script the calc something like:
If ( IsEmpty (YourField) )
SetField (YourField ; Calc expression here )
and launch it on record commit or as appropriate.
This approach will shove the calculated value in there, but only if the field is empty (not over-ridden).
It's also possible to set up a data field such as text, number or date with an auto-enter calculation. This is through a dialog you can open by double clicking the field in Manage | Database | Fields.
You can leave the "do not replace existing value" option selected and then the calculation will enter a value when the record is first created, but a user can still edit the value in the field when needed.
I like your idea but it didnt showed me the calculation result but allowed me to enter in the field like an normal text or number field...I also set the "do not replace existing value" but still no use...Please help me with the issue....
Actually my database is collecting values from fix 5 generic type of values...I am displaying records through portal....
The auto-enter only occurs for new records or when a field referenced in the calculation and from the same record is modified. Existing records will not update to show the calculated value automatically, though there are ways to get them to update: Updating values in auto-enter calc fields without using Replace Field Contents
If that's not the issue, you'll need to post the calculation that you tried to use.