Mustafa,
I have had the same issue with a Java hybrid application that refuses to read all the text when initially reading however, if there is a scroll bar and you are able to use it; scroll all the way to the bottom, then back to the top. This should make the information visible when reading the field.
It worked for me, the only issue you may have if the quantity of information. I know I had to create a calculation stage to determine the scroll time/clicks depending on visible items within the starting window. Subsequently when there was a lot of items, this took a while due to send keys clicks and window validation.
Give it a go and let me know how you get on.
Thanks,
James