About CASE Statement

Hi all,

Does anyone know what's wrong of the following code?

CASE SUBSTR(INP_REP_TYPE, 1, 3)
WHEN '100' THEN
WS_H4 := WS_H1;
WS_TEXT_HEAD := SUBSTR(WS_H1, 48, LENGTH(WS_H1));
WHEN '010' THEN
WS_H4 := WS_H2;
WS_TEXT_HEAD := SUBSTR(WS_H2, 52, LENGTH(WS_H2));
WHEN '001' THEN
WS_H4 := WS_H3;
WS_TEXT_HEAD := SUBSTR(WS_H3, 59, LENGTH(WS_H3));
WS_TOTAL_LINE := 'ALL BANKING GROUPS';
END CASE;

After compile, it showed the following error message:

PLS-00103: Encountered the symbol "CASE" when
expecting one of the following:
begin declare end exception exit for goto if loop mod null
pragma raise return select update while <an identifier>

Regards,
TazBon

is that the full code?

have u got begin somewhere?