PDF Architect issues

Hi, my name is Federico, from Argentina. About 3 months ago, i have  Pdf Architect licenses for editing PDF´s.

At first i used software without problems. About a month ago, when i try modify a pdf document, below the tool bars, appears this text: "There is no available glyph(s) for this symbol. The font used in this document is not installed on your system. In order to edit the text in this document, you need to use a different font or install the specific font on your computer system"

Please, can you help me?