Equations embedded in XML literals (Visual Basic)

I'm getting stumped by what I hope is a simple problem. I'm trying to embed a simple formula incrementing a variable to act as a "line number" for an XML document. Writing literal XML in visual basic. Here's what the code looks like:

<%= From d In orderData
                                       Select <ItemOut quantity=<%= d.OrderQuantity %> lineNumber=<%= i %>>
                                                  <ItemID>
                                                      <SupplierPartID><%= d.VendorPartNo %></SupplierPartID>
                                                  </ItemID>
                                                  <ItemDetail>
                                                      <UnitPrice>
                                                          <Money currency="USD"><%= d.PricePerPackage %></Money>
                                                      </UnitPrice>
                                                      <Description xml:lang="en"><%= d.Description %></Description>
                                                      <UnitOfMeasure><%= d.OrderUOM %></UnitOfMeasure>
                                                  </ItemDetail>
                                                  <%= i = i + 1 %>
                                              </ItemOut>
                                       %>

I was expecting each iteration of d in OrderData to tick i + 1, however, it is simply returning "false". See the output XML here:

<ItemOut quantity="1" lineNumber="1">
        <ItemID>
          <SupplierPartID>99999</SupplierPartID>
        </ItemID>
        <ItemDetail>
          <UnitPrice>
            <Money currency="USD">0.00</Money>
          </UnitPrice>
          <Description xml:lang="en">Tub and Tile Caulk Biscuit</Description>
          <UnitOfMeasure>cs</UnitOfMeasure>
        </ItemDetail>false</ItemOut>
      <ItemOut quantity="1" lineNumber="1">
        <ItemID>
          <SupplierPartID>999999</SupplierPartID>
        </ItemID>
        <ItemDetail>
          <UnitPrice>
            <Money currency="USD">0.00</Money>
          </UnitPrice>
          <Description xml:lang="en">Tub and Tile Caulk Almond</Description>
          <UnitOfMeasure>cs</UnitOfMeasure>
        </ItemDetail>false</ItemOut>

Is it possible to do this sort of thing? I even tried making a call to a function instead:

lineNumber=<%= incrementI(i) %>>

But that also results in "false" as the output. What am I missing here? Thank you for your help in advance!

Visual Studio 2013