HelloWorld出错了，哪位大哥指点一下？

<?xml version="1.0" encoding="utf-8"?>
<DependentLayout
        xmlns:ohos="http://schemas.huawei.com/res/ohos"
        ohos:width="match_parent"
        ohos:height="match_parent"
        ohos:background_element="#000000">
    <Text
            ohos:id="$+id:text"
            ohos:width="match_content"
            ohos:height="match_content"
            ohos:center_in_parent="true"
            ohos:text="Hello World"
            ohos:text_color="white"
            ohos:text_size="32fp"/>
    <Button
            ohos:id="$+id:button"
            ohos:width="match_content"
            ohos:height="match_content"
            ohos:text_size="19fp"
            ohos:text="Next"
            ohos:top_padding="8vp"
            ohos:bottom_padding="8vp"
            ohos:right_padding="80vp"
            ohos:left_padding="80vp"
            ohos:text_color="white"
            ohos:background_element="$graphic:button_element"
            ohos:center_in_parent="true"
            ohos:align_parent_bottom="true"/>
</DependentLayout>
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