Problems with displaying node

In my XML, I have some <para> with an attribute or not. I want use this
attribute to make a test. If the attribute is != null then I don't want to
display the contains of <para>.

Here is my XML:

<document>
<para name="introduction">
    Contains of the introduction
</para>

<para name="author" invisible="yes">
    Name of the author
</para>

<para name="para1">
    Contains of the para1
</para>

<para name="interpara" invisible="yes">
    Contains of the interpara
</para>

</document>

In my XSL, I have make some condition on the @invisible like this:

<xsl:template match="//para">
<xsl:if test="//para/@invisible!='yes'">
<xsl:value-of select="//para"/>
</xsl:if>
</xsl:template>

But the output is binary..and don't take into a count my attribute..
Thanks for help