Creating List with xsl:function

Hi All,

I am having trouble creating list in XSLT 2.0. I am trying an example from
XSLT 2.0 3rd edition (chapter 10) (Wrox), but having trouble getting it to
work in my stylesheet.

The example to the book shows:

	<xsl:function name="f:olist-format" as="xs:string">
		<xsl:param name="node" as="node()"/>
		<xsl:sequence select="('1', 'a', 'i', 'A', 'I')
[count($node/ansestor::olist) mod 5 + 1] "/>
	</xsl:function>


<xsl:template match="olist">		
			<ol class="enum{$f:list-format(.)}"> 
				<xsl:apply-templates/> 
			</ol>
</xsl:template>

Mine looks like this:

Namespace in SCHEMA is "ACM".
	
<xsl:function name="ACM:list-format" as="xs:string">
	<xsl:param name="node" as="node()"/>
	<xsl:sequence select="('1', 'a', 'i', 'A', 'I')
[count($node/ansestor::list) mod 5 + 1] "/>
</xsl:function>

<xsl:template match="ACM:list">
	<xsl:for-each select="ACM:Para">
			<ol class="enum{ACM:list-format(.)}">
				<xsl:apply-templates/>
			</ol>
	</xsl:for-each>
</xsl:template>

I receive this error:

"Invalid XPath 2.0 expression Unexpected token. Probably missing valid axis
name before '::'  - "::ACM:list) mod 5 + 1] ""

I assume I am not declaring the Function properly. Can the XSL:Function be
placed anywhere in the stylesheet as long as it is a child of
</xsl:stylesheet>? Do I need to declare a namespace for a function?  And if
so how? I am a little lost.

Thanks,

Phil