I think that you are probably running up against the limitation that Word
has on the number of columns in a table. For that reason, data sources
created through the mailmerge wizard in Word XP and later are saved as .mdb
(Access) files where the limit is 256 fields.

--
Hope this helps.

Please reply to the newsgroup unless you wish to avail yourself of my
services on a paid consulting basis.

Doug Robbins - Word MVP

"thenin" wrote in message
...
Hello
Have a problem here and I have not found anything about this on MS Office
Support site.

We use a generated HTML file as a datasource for the Mail Merge from our
application.

The problem arizes when the number of Merge Fields defined in the HTML
file
exceeds 63(!).

After I open the datasource in Merge Document I can see only first 63
Merge
Fields in the 'Insert Merge Field' dialog. And the 63rd merge field name
is
composed of the names of merge fields which come after the 62th field(!)

However when I use the comma-separated file or an SQL datasource I do not
experience any problems - I have tried with datasources with more than 100
fields.

Do you happen to know what the problem may be?