I need to add all BillingDetails/Amount. Does the sum function recognize -1000.00 (negative numbers)?

sum(BillingDetails/Amount)

<BillingDetails>
      <StatementType>string</StatementType>
      <Amount>11393.17</Amount>
</BillingDetails>
<BillingDetails>
      <StatementType>string</StatementType>
      <Amount>14393.17</Amount>
</BillingDetails>
<BillingDetails>
      <StatementType>string</StatementType>
      <Amount>-1000.17</Amount>
</BillingDetails>

Yes, if it doesn't in your case then you need to show your code, the context node maybe incorrect for the XPath you're using.

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Joe (Microsoft MVP - XML)

Thanks. It was indeed a context issue.