Many to Many mapping problem

[bosuch]

I have a scenario where I need to replace some elements in an existing message with the contents of another message. Message #2 (the existing message) looks like this:

<Root>
<Loop2300>
<Loop2400>
<LXSegment>
<LX01_AssignedNumber>1</LX01_AssignedNumber>
</LXSegment>
<HCPSegment>
<HCP02_Amount>0</HCP02_Amount>
</HCPSegment>
</Loop2400>
<Loop2400>
<LXSegment>
<LX01_AssignedNumber>2</LX01_AssignedNumber>
</LXSegment>
<HCPSegment>
<HCP02_Amount>0</HCP02_Amount>
</HCPSegment>
</Loop2400>
</Loop2300>
</Root>

And message #1 (the new data) looks like this:


<Root>
<Header>
<Detail>
<ServiceLine>1</ServiceLine>
<Amount>10.4</Amount>
</Detail>
<Detail>
<ServiceLine>2</ServiceLine>
<Amount>1.2</Amount>
</Detail>
</Header>
</Root>

I want to match up the LX01_AssignedNumber in the first message to the ServiceLine in the second message, and replace the appropriate amounts, so that the output winds up looking like this:

<Root>
<Loop2300>
<Loop2400>
<LXSegment>
<LX01_AssignedNumber>1</LX01_AssignedNumber>
</LXSegment>
<HCPSegment>
<HCP02_Amount>10.4</HCP02_Amount>
</HCPSegment>
</Loop2400>
<Loop2400>
<LXSegment>
<LX01_AssignedNumber>2</LX01_AssignedNumber>
</LXSegment>
<HCPSegment>
<HCP02_Amount>1.2</HCP02_Amount>
</HCPSegment>
</Loop2400>
</Loop2300>
</Root>

I thought I could just use an Equal functoid and compare Service Line to LX01_AssignedNumber, then a Value Mapping functoid, but I wind up with 10.4 for both of them. How would I solve this?

Thanks!