getting blank page after creating custom layout

I have created custom layout as below

created 3-columns-double-footer.xml file inside Magento_Theme/page_layout folder

    <?xml version="1.0"?>
<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_layout.xsd">
    <update handle="3columns"/>
    <referenceContainer name="page.wrapper">
        <container name="footer-bottom" as="footer-bottom" after="footer" label="Footer Bottom" htmlTag="footer" htmlClass="page-footer-bottom">
            <container name="footer-bottom-content" as="footer-bottom-content" htmlTag="div" htmlClass="footer content" />
        </container>
    </referenceContainer>
</layout>

and also created layouts.xml file inside Magento_Theme folder as below

 <?xml version="1.0" encoding="UTF-8"?>
<page_layouts xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/PageLayout/etc/layouts.xsd">
    <layout id="3-columns-double-footer">
        <label translate="true">3 Columns Double Footer</label>
    </layout>
</page_layouts>

But after clearing the cache when I select this custom layout for my cms page it is giving me blank page.

can anyone have any idea.