Why do I see ?'s or black boxes in my PDF? Asp.net c# RDLC

I have enterd some data in Hindhi language in my database i have to use this data to generate a pdf but the data is showing in squre why this happens? I have also installed the hindhi font size.But the strange thing is before entering hindhi data i have enterd some of the data in english and those are showing in the hindhi font?Does anyone have a solution for this?