Data type mismatch in criteria expression

I have an Access database with these tables and settings:

Keyword
* Keyword_ID (Autonumber)
Keyword (text)

DocumentKeyword
* Document_ID (long integer)
* Keyword_ID (long integer)

Document
* Document_ID (Autonumber)
Title (text)
Author (text)
Location (text)

DocumentTopic
* Document_ID (long integer)
* Topic_ID (long integer)

Topic
* Topic_ID (Autonumber)
Topic (text)

UserTopic
* User_ID (long integer)
* Topic_ID (long integer)

User
* User_ID (Autonumber)
Username (text)
Password (text)
Security_ID (text)
Email (text)

Then I set up a query table which made the SQL code:

SELECT [Document].[Document_ID], [Topic].[Topic_ID], [Document].[Title], [Document].[Author], [Document].[Location], [Topic].[Topic]
FROM (Document INNER JOIN DocumentTopic ON [Document].[Document_ID]=[DocumentTopic].[Document_ID]) INNER JOIN Topic ON [DocumentTopic].[Topic_ID]=[Topic].[Topic_ID];

I am concerned about the square brackets (or whatever they are called), when I take them out they appear again next time I open the query.

Anyway all the ASP pages that use this query say "Data type mismatch in criteria expression"

Any pointers would be much appreciated.
Thanks
Sara