Adding new Fonts is not working

I am trying to add new fonts while creating a PDF from HTML using Aspose.Pdf
below is the code:

   var fs = new FolderFontSource(Server.MapPath("fonts"));
   FontRepository.Sources.Add(fs);
   FontRepository.FindFont(@"GrifoSBold", true);
   FontRepository.FindFont(@"Mute-Regular", true);
   FontRepository.FindFont(@"Mute-Semibold", true);
   FontRepository.FindFont(@"glyphicons-halflings-regular", true);

This code worked once.
I am not sure what i am missing now

Thanks in Advance

@abyjoshi2891,

Thanks for contacting support.

Can you please share source file along with version details. Also please share if you changed version of PDF.