Syntax error

hello all,

SELECT B~MATNR

INTO TABLE LT_FINAL

FROM /SAPAPO/MATLOC AS A

INNER JOIN /SAPAPO/MATKEY AS B ON A_{MATID EQ B}MATID

INNER JOIN /SAPAPO/LOC AS C ON A_{LOCID EQ C}LOCID

WHERE C~LOCID EQ LT_ORDKEYS-LOCID.

Error : lt_ordkeys is a table without header line.

My Declaration is.

data : LT_ORDKEYS TYPE /SAPAPO/OM_ORDKEY_TAB,

But i cannot declare like

LT_ORDKEYS TYPE /SAPAPO/OM_ORDKEY_TAB with header line.

Then i cannot pass it to Fm CALL FUNCTION '/SAPAPO/OM_ORDER_GET_DATA'

importing parameter : et_ordkeys.

How to solve this ?