Hi, Samuel,
As we found, there was nothing wrong with your spec. There were a couple of tax setup problems in PO though. Per the Help, the tax statuses in the PO company profile should be the same as those in AP. There were none in AP so you set them up.
And, within the tax group itself, the jurisdiction was set to a costing methog of 'None - GL only'. This means to send the tax to the GL but not to AP so that the tax is never really payable by the AP vendor. When you change this to 'Accounts Payable' and repost the order, the taxes correctly display in the Total Payable by Vendor on the order Totals tab and are included in the Total Including Tax spec code on your spec.
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Regards,
Softrak Tech Support