Can we use use ' join ' with in a function module !!!

In my case its giving an error

SELECT vbak~vbeln

vbak~erdat

vbak~vkorg

ABRVW

augru

kunnr

posnr

matnr

vbap~vkaus

vbap~spart

vbap~netwr

vbap~waerk

kwmeng

kondm

mvgr1

mvgr2

mvgr3

mvgr4

mvgr5

FROM vbak AS vbak INNER JOIN vbap AS vbap

ON vbak_{vbeln EQ vbap}vbeln

INTO corresponding fields of TABLE tvbak

WHERE vbak~vbeln = vbeln1.

for the above code which is a part of function module.its

giving run time exception.....as its saying it cant read data from table VBAK.....NEED HLP