Changing the form field tab order does not work

Product: C++ SDK

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Changing the tab order for form fields of a page doesn’t work.

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When i change the entry for the tab order in a page object, the correct entry is selected in the viewer (for example in Adobe Acrobat). But the tab order of the fields itself remains the same.
I try to set the tab order from structural to row the following way:

	for(int nSeite = 0; nSeite < dokument.nSeiteAnzahl; ++nSeite)
		pdftron::PDF::page page = dokument.pPDFSeite[nSeite]->page;
		pdftron::SDF::Obj tabs = page.GetSDFObj().FindObj("Tabs");

		if (tabs)

I also tried to refresh the appearances:


But this also doesn’t have an effect.

Am i something missing here?