Weird database related PHP issue

Question

Basically I have a regular page that lists a bunch of
Candidates from a table :
CandidateID, Candidate
They link through to a details page on CandidateID
On the listing page, I also have a link to an Edit Candidate
Details page, using :
[CODE]
<a href="editCandidateEmail.php?CandidateID=<?php echo
$row_Candidates['CandidateID']; ?>"><img
src="../Images/edit7.gif" border="0" width="28px" height="18px"
/></a>
[/CODE]
Which works just as it should. So far so good.
On my details page, I have the exact same link to the edit
deatils page, using :
[CODE]
<a href="editCandidateEmail.php?CandidateID=<?php echo
$row_Candidates['CandidateID']; ?>"><img
src="../Images/edit7.gif" border="0" width="28px" height="18px"
/></a>
[/CODE]
The weird thing is that it works sometimes, but not others.
The error is :
You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to
use near '' at line 1
And the URL is just missing the ID off the end of the link,
so looks like :
../editCandidateEmail.php?CandidateID=
Instead of
../editCandidateEmail.php?CandidateID=1234
The recordset is named 'Candidates', and there is a
CandidateID present.
Any clue as to what might be causing this?
Cheers.

Answer 1

d'oh! Figured out what was happening - there were two
recordsets on the details page, and one involved a join to another
table - so if a CandidateID wasn't present in the other look up
table, it wasn't being referenced by that recordset - so I just
changed those links to refer to the simple recordset that referred
directly to the Candidates table.