第72行第FN_GETBASE64没有定义怎么回事？

    p_item                in apex_plugin.t_page_item, -- Holds item name, label and custom attributes
    p_plugin              in apex_plugin.t_plugin,    -- The plugin name
    p_value               in varchar2,                -- Is the field value of the item
	p_is_readonly         in boolean,                 -- Should the item be readonly
    p_is_printer_friendly in boolean
	)
    return apex_plugin.t_page_item_render_result
IS

	num01		  number;
	num02		  number;
	tmpNum		  number;
	opCode		  number;
    opName    	  VARCHAR2(30);
	opName_img	  clob;
	op			  VARCHAR2(30);
    -- Apex mandates that the PLSQL render function for a plugin returns apex_plugin.t_page_item_render_result.
    l_result      apex_plugin.t_page_item_render_result;
    v_width number:=p_item.element_width;
    v_type number := p_item.attribute_01;
    v_SUBMIT VARCHAR2(200) := p_item.attribute_02;
    lv_string varchar2(32676);
    v_captchaValue varchar2(100);
BEGIN
    
    if not apex_collection.collection_exists('APEXCAPTCHA_RESAULT') then 
       apex_collection.create_collection('APEXCAPTCHA_RESAULT');
    end if;
    
    
    IF v_SUBMIT='Y' THEN
        v_SUBMIT:='onkeypress="return apex.submit({request:'''||p_item.name||''',submitIfEnter:event})"';
    ELSE
        v_SUBMIT:='';
    END IF;


    num01:=round(dbms_random.value(0,10));
    num02:=round(dbms_random.value(0,10));
    opCode:=round(dbms_random.value(1,3));

    if opCode=1 then
        opName:='plus';
        op:='+';
    elsif opCode=2 then
        opName:='multiplied by';
        op:='*';
    else
        if num01<num02 then
            tmpNum:=num01;
            num01:=num02;
            num02:=tmpNum;
        end if;
        opName:='minus';
        op:='-';
    end if;



    htp.p('<input type="text" '||v_SUBMIT||' autocomplete="off"  style="direction:ltr; order:1; text-align:center" name="'||p_item.name||
    '" id="'||p_item.name||'" required=""'||
    'size="'||v_width||'" '||
    'maxlength="2" '||
    'class="text_field apex-item-text apex-item-has-icon '||p_item.element_css_classes||'" '||
    p_item.element_attributes||
    '/>');
    
    
     if v_type=1 then
        opName_img:=FN_GETBASE64(num01||' '||op||' '||num02);
    htp.p('<img src="'||opName_img||'" style="order:2;width:80px;height:30px">');
    else
        htp.p(num01 ||' '||opName||' '|| num02);
    end if;
    
    
    if p_item.icon_css_classes is not null then
        htp.p('<span class="apex-item-icon fa '||p_item.icon_css_classes||'" aria-hidden="true"></span>');
    end if;

    execute immediate 'select '||num01||op||num02||' from dual' INTO v_captchaValue ;
    APEX_COLLECTION.TRUNCATE_COLLECTION ( 'APEXCAPTCHA_RESAULT');
    apex_collection.add_member(
        p_collection_name => 'APEXCAPTCHA_RESAULT',
        p_c001 =>            v_captchaValue
    );
    
    RETURN l_result;

END render_captcha ;

FUNCTION validate_captcha (
    p_item   IN     APEX_PLUGIN.t_page_item, 
    p_plugin IN     APEX_PLUGIN.t_plugin,    
    p_value  IN     VARCHAR2)                
    RETURN APEX_PLUGIN.t_page_item_validation_result
IS
	l_result       	apex_plugin.t_page_item_validation_result;
    v_captchaValue  varchar2(200);
BEGIN	
    BEGIN
    
    select nvl(C001,1) into v_captchaValue
        from apex_collections
    where collection_name = 'APEXCAPTCHA_RESAULT';
		IF upper(v_captchaValue) = upper(p_value) THEN
			return l_result;
        ELSE
			l_result.message := 'wrong captcha!';
			return l_result;
		END IF;       
    EXCEPTION WHEN OTHERS THEN
        l_result.message := 'captcha exception Error!'; 
        return l_result;     
	END;	
	RETURN l_result;
END validate_captcha;