I cannot see the scanned pdf's...why is that? should i use a 3rd party app?

thanks

Because the text inside the PDF is a raster image (like a picture) and not text (like what a work processor can use). Thus the attachment converters don't know how to deal with these files. Or at least I can't get my ancient BES server to convert them correctly.

do i have to use a 3rd party software to be able to read this?

Take a look at RepliGo Professional for BlackBerry...

It works very well and will allow you view even graphical PDF files...