ABAP Code Error

Hi,

I have following code in a query and I get an error (Incorrect logical expression: Operator (e.g. "AND") or end of    expression expected)when I try to save:

clear Z_BILL_AMOUNT2.

IF VBAK-AUART = 'ZASA'.

Z_BILL_AMOUNT2 = Z_QUOTE_VALUE_LEFT.

Z_BILL_AMOUNT = Z_VBAP_NETWR_SCHEDULE.

ELSEIF VBAK-VBTYP = 'G'

  and VBAP-ABGRU = 'Z1'

Z_BILL_AMOUNT2 = VBAP-NETPR.

ELSE.

Z_BILL_AMOUNT2 = Z_BILL_AMOUNT.

ENDIF.

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Do you know what is missing or needs to be changed?

thanks

Joe