How do I specify "not equals to" when comparing strings in an XSLT <xsl:if>?

Currently i have a xsl with following code where I'm trying print out "count" only if it is not equal to N/A. but seems like "!=" is not working.

<xsl:for-each select="Directory/Match">
    <xsl:if test = "Count != N/A">
        <tr>
            <td><xsl:value-of select="@bookName" /></td>
            <td><xsl:value-of select="@AuthorName" /></td>
            <td><xsl:value-of select="Count" /></td>
        </tr>
    </xsl:if>
</xsl:for-each>

However, it works if I try to compare it with numeric value.

Example:

<xsl:if test = "Occurrances != 0">

Can someone please tell me: If I would like to compare strings what can I use?

As Filburt says; but also note that it's usually better to write

test="not(Count = 'N/A')"

If there's exactly one Count element they mean the same thing, but if there's no Count, or if there are several, then the meanings are different.

6 YEARS LATER

Since this answer seems to have become popular, but may be a little cryptic to some readers, let me expand it.

The "=" and "!=" operator in XPath can compare two sets of values. In general, if A and B are sets of values, then "=" returns true if there is any pair of values from A and B that are equal, while "!=" returns true if there is any pair that are unequal.

In the common case where A selects zero-or-one nodes, and B is a constant (say "NA"), this means that not(A = "NA") returns true if A is either absent, or has a value not equal to "NA". By contrast, A != "NA" returns true if A is present and not equal to "NA". Usually you want the "absent" case to be treated as "not equal", which means that not(A = "NA") is the appropriate formulation.

If you want to compare to a string literal you need to put it in (single) quotes:

<xsl:if test="Count != 'N/A'">