Complex XPath Expression

Hello,

I have an xpath query that works in each of it's respective pieces but
does not return a desired result when combined.

Here is the complete expressions, followed by an explanation of it's parts:

COMPLETE:
recordset[@rsName='Codes']/record[field[@fieldname='Section']='2'][field[@fieldname='ID']
= recordset[@rsName='Memberships']/record[1]/field[@fieldname='RefEntryActivityID']]


1ST PART:
recordset[@rsName='Codes']/record[field[@fieldname='Section']='2'][field[@fieldname='ID']

>> Alone, this correctly produces a result set of 15 matching nodes.

2ND PART:
recordset[@rsName='Memberships']/record[1]/field[@fieldname='RefEntryActivityID']

>> Alone, this retrieves the node who's value is 2913.

If I rewrite the complete expression like this:
recordset[@rsName='Codes']/record[field[@fieldname='Section']='2'][field[@fieldname='ID']
= 2913]

>> I do match one node which is the desired result.

What is wrong with the complete expression?  Both the 1st part and 2nd
part behave accordingly, but combined not.

Thanks for the help!

Karl