Show layered navigation on catalog search results page in magento

Question

When I add a specific subcategory to my query string on my search results page I can see the chosen refinements list and filter options for other categories, price ranges, etc. However if I only do a keyword search I do not see any filter options. How can I set my results page to show all available filters with just a keyword search?

Edited to add - here is the layout xml:

               <catalogsearch_result_index translate="label">
    <label>Quick Search Form</label>
    <update handle="page_two_columns_left" />
    <reference name="root">
        <action method="setTemplate"><template>page/1column.phtml</template></action>
    </reference>
    <reference name="left">
    </reference>
    <reference name="content">
        <block type="catalogsearch/layer" name="catalogsearch.leftnav" after="currency" template="catalog/layer/view.phtml"/>

        <block type="catalogsearch/result" name="search.result" template="catalogsearch/result.phtml">
            <block type="catalog/product_list" name="search_result_list" template="catalog/product/list.phtml">
                <block type="catalog/layer_view" name="filter" template="catalog/layer/view.phtml"/>
                <block type="catalog/product_list_toolbar" name="product_list_toolbar" template="catalog/product/list/toolbar.phtml">
                    <block type="page/html_pager" name="product_list_toolbar_pager"/>
                </block>
                <action method="setColumnCount"><count>3</count></action>

                <action method="addColumnCountLayoutDepend"><layout>empty</layout><count>6</count></action>
                <action method="addColumnCountLayoutDepend"><layout>one_column</layout><count>5</count></action>
                <action method="addColumnCountLayoutDepend"><layout>two_columns_left</layout><count>4</count></action>
                <action method="addColumnCountLayoutDepend"><layout>two_columns_right</layout><count>4</count></action>
                <action method="addColumnCountLayoutDepend"><layout>three_columns</layout><count>3</count></action>
                <action method="setToolbarBlockName"><name>product_list_toolbar</name></action>
            </block>
            <action method="setListOrders"/>
            <action method="setListModes"/>
            <action method="setListCollection"/>
        </block>
    </reference>
</catalogsearch_result_index>

Here is a screen shot of the page prior to any filters on the search:

Here is one with a category filter added:

Answer 1

It may depends of the number of results.

Open the search settings at admin - system - configurations - catalog - catalog search and find the option "Apply Layered Navigation if Search Results are Less Than"

Enter "0" to enable layered navigation for any number of results.

Answer 2

replace xml

<reference name="left">

</reference>

with

<reference name="left">
<block type="catalogsearch/layer" name="catalogsearch.leftnav" after="currency" template="catalog/layer/view.phtml"/>

</reference>

and remove from name='content'