Hi, the tax attribute road is a dead end, drop it. Attributes in the tax engine belong to an entity record — item, customer, G/L account — and their values come from the attribute mapping, so a document field like Document Type never reaches the symbol store. That is exactly what "no Script Symbol Value" is telling you.
On the first attempt I'd look earlier than the condition. If the case is not executed at all, most likely nothing is calling tax calculation for your new type — the India subscribers are written around the base enum values, and extending the enum doesn't extend them. Check where sales tax calculation gets triggered on the Sales Line in the Tax Base app, I wouldn't trust my memory on the object name, better look in your own version.
If you can, I'd keep Document Type as Order or Invoice and put a separate Proforma boolean on the header, then condition on that field. Less fighting with the engine.
Glad to help - follow up if anything is unclear.
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Regards,
Grigorios Mavrogeorgis
Business Central Consultant & AL Developer
Work: Gmsoft Limited
Blog: insidebusinesscentral
LinkedIn: linkedin.com/in/gregorymavrogeorgis
