SOS: indexed but not searchable for all attributes

In my setup I have a mysql table that has three columns:
column A is id column
column B is TEXT data type column
column C is varchar(255) column
column D is varchar(255) column

I am indexing this table using ferret/acts_as_ferret and I am made sure
to index all the above specified fields. Also once indexing is done, and
when retrieve the record by find_by_contents(“id:…”), I can see all
the data has been indexed including Column B,C,D data.

However I am able search only on column A and column B but not able to
search on column C and D. I am not sure why that is the case. So
find_by_contents(“C:…”) or "find_by_contents(“D:…”) returns me ZERO
results. whereas B and A are fine in terms of search. I can also see
that column C and column D are indexed because when I retrieve by B and
A, I can see contents of the record that shows attributes for column C
and D.

Any help would be greatly appreciate if somebody has idea as to why I
can’t search by C or D.

Regards
Rajiv