Using Variable in XPath expression with input elements having prefixes

I have 3 employee records as below. In my XSLT I have created a variable with line numbers 1, 2, & 3 and then looping through each of these lines to print fname. But it is not working.

Below is the input xml:

<tns:empLines>
    <tns:empLine>
        <can:fname>John</can:fname>
        <can:lname>Doe</can:lname>
        <can:age>20</can:age>
        <can:lineNumber>1</can:lineNumber>
    </tns:empLine>
    <tns:empLine>
        <can:fname>James</can:fname>
        <can:lname>Douglas</can:lname>
        <can:age>24</can:age>
        <can:lineNumber>2</can:lineNumber>
    </tns:empLine>
    <tns:empLine>
        <can:fname>Joe</can:fname>
        <can:lname>Sims</can:lname>
        <can:age>30</can:age>
        <can:lineNumber>3</can:lineNumber>
    </tns:empLine>
</tns:empLines>

Below is my xslt:

<xsl:stylesheet version="1.0" xmlns:xsl="http://ift.tt/tCZ8VR" xmlns:fo="http://ift.tt/vyPH5E">
    <xsl:template match="/">
        <xsl:variable name="lines">
            <line num="1"/>
            <line num="2"/>
            <line num="3"/>
        </xsl:variable>
        <root>
            <xsl:for-each select="$lines/line">
                <pc>
                    <xsl:value-of select="//*[local-name()='empLines']/*[local-name()='empLine'][*[local-name()='lineNumber']=current()/@num]/*[local-name()='fname']/text()"/>
                </pc>
            </xsl:for-each>
        </root>
    </xsl:template>
</xsl:stylesheet>