Enterprise portal, AX 2009, receipts attched, View receipts,Expense management,T&E, document handing in T&E,EP issue

HI All,

I have an issue while view the attached receipts in enterprise portal-AX2009.

I have attached the 4 MB pdf file using “Attach receipts” link in Expense reports form. But when i tried to view the attached receipts using “View receipts”, the page throw error.
“Unable to render the page due to error. please contact your system administrator”.

When i attach 2 MB or 3MB file i am able to view in the View receipts form, but when i attach more than 3 MB it throws error. At the same time, if i import word doc or excel doc it doesnt throw any error, the page display details correctly.

Issue is only for attaching PDF file in enterprise portal. Kindly help how to increase the PDF file attachment size for enterprise portal.