MS Access help with boolean values

One of the attributes in my db is of type boolean, which when linked to MS
Access assumes type Yes/No. However, when I attempt to query through
Access for all tuples that are 'true' I get the following messages returned
by Access, and the log file was no help.

"ODBC--call failed"

"Error while executing the query (non-fatal);
ERROR: Unable to identify an operator '=' for types 'bool' and 'int4'
You will have to retype this query using an explicit cast (#-1)"

I have tried the following, all of which have given me the same error message:
"SELECT ......... FROM organizations WHERE FROM
(((organizations.submit_flag)=-1));"
"SELECT ......... FROM organizations WHERE FROM
(((organizations.submit_flag)=Yes));"
"SELECT ......... FROM organizations WHERE FROM
(((organizations.submit_flag)=True));"

I am using:
MS Access '97 w/ pgsql-odbc-07.01.0004 and PostgreSQL 7.0.3

I am kind of new to ODBC, so I apologize in advance, but I would appreciate
any help.