I have a FMP16 file where I insert pdf in a container manually, work fine.
I try to put a button that would perform the same task, prompting the user to choose the pdf file.
Go to Field [myFile::FieldName]
Insert PDF 
Show Custom Dialog [ "error message"; Get(LastError)]
return error 3
according to Filemaker error codes
Command is unavailable (for example, wrong operating system or mode)
Work fine manually
What is it I'm missing?