Hi Sukhman
Maybe you didn't save your form in Acrobat Pro properly - as Larry mentioned. Can you check your process again, which should be:
Export the ID file as an Interactive PDF.
Open the PDF form in Acrobat XI and then:
File > Save As Other > Reader Extended PDF > Enable More Tools (includes for fill-in & save). . . Your users will be able to fill in the form and save it (assuming they have the later versions of Acrobat Reader).
Make sure you keep a copy of your original PDF with a different file name as once you've created a Reader Enabled PDF Form you can't change it.
Derek