Please help.....Problems posting to a relational database

I'm developing a really simple database in Access which comprises of three linked tables. So far using I can post to the individual tables when I dont have any relationships between them. However when I try to INSERT new info into the tables when connected by relationships I get the error ---

You cannot add or change a record because a related record is required in table 'universities'.

Do I need to connect the related tables beforehand using SQL ie.

SQL="SELECT fname, lname, email, carID, carName, carrate "

SQL=SQL & "FROM Clients, Cars "

SQL=SQL & "WHERE email = 'jdoe@whatever.com' "

SQL=SQL & "AND Clients.carID = Cars.carID"

so far I have the following code......

<%@ Language = VBscript %>
<%


'Grab variables from the querystring.

namevariable=Request.Querystring("name")
emailvariable=Request.Querystring("email")
telephonevariable=Request.Querystring("tel")
descriptionvariable=Request.Querystring("description")

unit_namevariable=Request.Querystring("unit_name")
unit_urlvariable=Request.Querystring("unit_url")
unit_descriptionvariable=Request.Querystring("unit_description")
unit_scenariovariable=Request.Querystring("unit_scenario")
unit_casestudyvariable=Request.Querystring("unit_casestudy")
unit_fundingvariable=Request.Querystring("unit_funding")

'Create the INSERT statement for a brand new client.

SQLpeople="INSERT INTO people (name, email, tel, description)"
SQLpeople=SQLpeople & "VALUES ('" & namevariable & "', '" & emailvariable & "', '" & telephonevariable & "', '" & descriptionvariable & "' )"

SQLunits="INSERT INTO units (unit_name, unit_url, unit_description, unit_scenario, unit_casestudy, unit_funding) "
SQLunits=SQLunits & "VALUES ('" & unit_namevariable & "', '" & unit_urlvariable & "', '" & unit_descriptionvariable & "', '" & unit_scenariovariable & "', '" & unit_casestudyvariable & "', '" & unit_fundingvariable & "')"


set connupdate = server.createobject("ADODB.Connection")
connupdate.open "Connect3"
connupdate.execute(SQLpeople)
connupdate.execute(SQLunits)


connupdate.close

%>


any help would be really really appreciated

thanks

Paul

I'm just guessing, but did you try switching the two execute statements?

connupdate.execute(SQLunits)
connupdate.execute(SQLpeople)

hope it helps