SharePoint 2013 Blog: sort posts by authors - sorting

Question

I'm trying to make a custom filter which sorts on authors (users) in the SharePoint 2013 blog. I'm working with XSL dataview and it's exported to a web part. I have a column called Author which gets the information from Created By. When I click on a user in the web part it shows all posts instead of the selected author. The URL is mysite/default.aspx?Author=FirstName LastName".
Code (default.aspx):
<xsl:template match="/" xmlns:x="http://www.w3.org/2001/XMLSchema" xmlns:d="http://schemas.microsoft.com/sharepoint/dsp" xmlns:asp="http://schemas.microsoft.com/ASPNET/20" xmlns:__designer="http://schemas.microsoft.com/WebParts/v2/DataView/designer" xmlns:SharePoint="Microsoft.SharePoint.WebControls">
<xsl:call-template name="dvt_1"/>
</xsl:template>
<xsl:template name="dvt_1">
<xsl:variable name="dvt_StyleName">RepForm3</xsl:variable>
<xsl:variable name="Rows" select="/dsQueryResponse/Rows/Row[not(#Author.title=preceding-sibling::Row/#Author.title)]" />
<xsl:call-template name="dvt_1.header">
<xsl:with-param name="Rows" select="$Rows" />
</xsl:call-template>
<div class="blogRefineByAuthorContainer">
<xsl:call-template name="dvt_1.body">
<xsl:with-param name="Rows" select="$Rows"/>
</xsl:call-template>
</div>
</xsl:template>
<xsl:template name="dvt_1.header">
<xsl:param name="Rows" />
<div class="blogRefineByAuthorEveryAuthor">Everyone</div>
</xsl:template>
<xsl:template name="dvt_1.body">
<xsl:param name="Rows"/>
<xsl:for-each select="$Rows">
<xsl:call-template name="dvt_1.rowview" />
</xsl:for-each>
</xsl:template>
<xsl:template name="dvt_1.rowview">
<div class="blogRefineByAuthorAuthorTitle">
<xsl:value-of select="#Author.title" />
</div>
</xsl:template>
Any ideas of what it could be? Between the first and last name there is a space in the URL, but I don't think it makes any sense. I have tried with %20 without any result.