ABAP Proxy

Hi ,

Iam doing File to ABAP Proxy scenario .when iam crating message interface in ABAP Proxy ( T.Code SPROXY ) . It will ask package , prefix

i given PACKAGE NAME YPRASAD ,

PREFIX NAME HTTP://http://isg.com/xi/training/FILE2ABAPPROXY31

it will shows error package yprasad has no use access to package interface SAI_TOOL.