[Koha] Problem with entering Personall Name

[Raphael Muonga]

I am currently entering manually Biblio records using MARC 21 Format
in Koha Live CD version 3.02.00.04 but I cannot type in  anything in
tag  100 subfield $a which suposed to be Personal name field since the
text area is like "prohibited" from typing in. So we used subfield $b
which accepts being  typed in but it is for something else. Hence we
are getting null information on Author when we query on author field
in SQL reports.  So how is Personal name entered using MARC 21
Cataloguing?

Thanking you in anticipation.

Raphael Chisanga Muonga