Convert searchable PDF to searchable PDF/A using distiller

Hi, i have a searchable pdf document and im trying to convert it to searchable pdf/a(RGB) using distiller,without success.The file converted to PDF/A but non searchable.I think that when i save the pdf as PostScript loses the attribute .I searched inside settings but i did not find anything related, can you please assist?

I have Acrobat Pro X.

Thanks