You have created Business Document (EX:Sales Order or Customer Invoice), when you preview the document, the Preview is fetching a wrong Form Template or no Template is being picked.
There are many reason that may cause this issue, they are
When you open the document in the Output History, the preview is in Form Template XYZ but when you preview the same document, the preview is in Form Template ABC.
The cause for the issue could be, after you submitted the document there might be a change in the Form Template or the Rule to pick the form template. In this case, the preview will always picks the form which suffices the current rule.
You might have maintained the rule for the Form Template (Form Template Selection) in such a way that, for a particular Org Unit (Ex: sales unit), this Form Template should be picked and for other Org Units different Form template.
Check the Rule for the Form Template in Form Template Selection view (Application and User Management work center) and correct the rule if applicable.
Note: You can manually change the template via Edit Output Settings but that would only be applicable for that document only, if you again check the Preview or Sends Confirmation to Account then it will pick the template based on the Form template rule defined.
You have maintained a empty Rule (without any parameter checked) in Form Template Selection. In this case, this Template will be picked always inspite any rule that set below this Template rule.
The Form Template is picked based on the Tax Country maintained in the document. So, check the Tax Country maintained in the document and if required create a new Form template if there is no Form template for that particular country variant.
In principle, The Form Template is picked in the document preview based on the Country Variant and Language, and the country variant is based on the Tax Country.
KBA , AP-SLO , Sales Order Processing , How To