When i set the caption of a Unicode aware Button to Arabic, the Arabic letters can't join as Arabic Script. As show as :

ﺍ ﻞ ﺲ ﻞ ﺍ ﻡ

What that is happening? The same project is working well in my Old PC & letters are joining automatically. Windows XP Processional SP2 installed on the newer machine & old was also as.