2 internal tabels

Dear all,

i select from the EKPO the PO number, PO position, material and quantity and write this into a internal table.

Now i want to select form EKET the delivery date only for the materials which are in my first internal table.

Thats my declatrion

DATA: iekpo type standard table of ekpo,
      zekpo type ekpo,
      ieket type standard table of eket,
      zeket type eket,
      imenge like ekpo-menge,
      i_menge(6) type c,
      izaehler1 type n,
      ztest,
      i_beleg like eket-ebeln,
      i_pos like eket-ebelp.

FIELD-SYMBOLS: <fs_menge1> TYPE ANY.
FIELD-SYMBOLS: <fs_beleg1> TYPE ANY.
FIELD-SYMBOLS: <fs_pos1> TYPE ANY.

.
.
.

* fill table from IEKET delivery date
loop at iekpo into zekpo.
i_beleg = 'EBELN'.
i_pos = 'EBELP'.
ASSIGN COMPONENT i_beleg OF STRUCTURE zekpo TO <fs_beleg1>.
ASSIGN COMPONENT i_pos OF STRUCTURE zekpo TO <fs_pos1>.
SELECT ebeln ebelp eindt
FROM eket
INTO CORRESPONDING FIELDS OF TABLE ieket
WHERE ebeln = <fs_beleg1> AND
ebelp = <fs_pos1>.
endloop.

Now i get a short dump: "Data objects in Unicode programs cannot be converted" at the seleciton line at the "Select ebeln ..." line

What is my mistake there.

For sure there is a better way to do this but i am a ABAP newbie.