[Zope] Having problems with SQL methods

[Peter Whysall]

I have an SQL method:

ID: insert_call_data.sql
TITLE: Insert Call Data Query
ARGUMENTS: user_id, call_type_id, call_desc, call_date, costcode_id

Query Template:

INSERT INTO calls 
(user_id,
 call_type_id,
 call_desc,
 call_date,
 costcode_id)
VALUES
(
<dtml-sqlvar user_id type=int>,
<dtml-sqlvar call_type_id type=int>,
<dtml-sqlvar call_desc type=string>,
<dtml-sqlvar call_date type=nb>,
<dtml-sqlvar costcode_id type=int>
);

When I do a change and test, I get the form to fill out, and I fill out
the arguments.

When I submit the query, I get this: 

Error, Missing Input: Missing input variable, user_id 

SQL used: 

Could not render the query template!

And this traceback:

Traceback (innermost last):
  File /opt/Zope/lib/python/ZPublisher/Publish.py, line 214, in
publish_module
  File /opt/Zope/lib/python/ZPublisher/Publish.py, line 179, in publish
  File /opt/Zope/lib/python/Zope/__init__.py, line 201, in
zpublisher_exception_hook
    (Object: insert_call_data.sql)
  File /opt/Zope/lib/python/ZPublisher/Publish.py, line 165, in publish
  File /opt/Zope/lib/python/ZPublisher/mapply.py, line 160, in mapply
    (Object: manage_test)
  File /opt/Zope/lib/python/ZPublisher/Publish.py, line 102, in
call_object
    (Object: manage_test)
  File /opt/Zope/lib/python/Shared/DC/ZRDB/DA.py, line 316, in manage_test
    (Object: insert_call_data.sql)
  File /opt/Zope/lib/python/Shared/DC/ZRDB/DA.py, line 295, in manage_test
    (Object: insert_call_data.sql)
  File /opt/Zope/lib/python/Shared/DC/ZRDB/DA.py, line 395, in __call__
    (Object: insert_call_data.sql)
  File /opt/Zope/lib/python/DocumentTemplate/DT_String.py, line 502, in
__call__
    (Object: <string>)
  File /opt/Zope/lib/python/Shared/DC/ZRDB/sqlvar.py, line 168, in render
    (Object: user_id)
Missing Input: (see above)

What am I doing wrong? 
Is this the best way of inserting data into tables?
Is there a document I should read before posting such newbie questions? (I
*have* read the Z SQL Methods User's Guide, but that seems to have nothing
on inserting data)

Regards

Peter.
--
Peter Whysall
Systems Engineer
Serco Technology