BTS2006 Rule engine problem

I have built a .Net component to perform some simple string manipulations 
like concatenation, padding etc. The component works great with BizTalk
2004, 
however, when I try to use the same component in a policy in BizTalk 2006,

it seems as if the methods are not being called. For example, 
I have a rule that performs a database lookup using a value that is a 
concatenation of 3 elements. The rule looks like this

If
Condition
	AND
		FromType is equal to SenderId
		ToType is equal to SAPNum
		FromValue is equal to BREHelper.Concat3Elements(XmlNode1, XmlNode2, 
XmlNode3)

Then
Action
	SenderNode = ToValue
	Assert XmlDoc

The FromType, ToType, FromValue and ToValues are vocabularies defined as 
columns from a database table. XmlNode1-3 are nodes from within the
message 
that is
passed to the rule engine. The nodes are of type System.String. I see the 
component, database connection and Xml message as facts. For some reason
the 
rule 
never gets fired. One strange think that I have observed trying to 
troubleshoot the problem is, if I replace XmlNode1-3 with hardcoded values

the rule fires.