A top level parameter

I would like to use top-level parameter for a javascript file name and another XML input file name to be included.
I have a trouble to deal with this top level parameter which works for javascript file but not for document().

The error message is saying from commend line like this:
saxon input.xml process.xslt param=pa > out.xml
>Recoverable error
>no more input

My erroneous XSLT is:
<xsl:param name="param">default</xsl:param>    //Top level parameter

<script xlink:href="{$param}.js" type="text/ecmascript"/>    //OK
<xsl:with-param name="count" select="count(document('{$param}.xml')node)"/>    //Error
 
Can somebody help me what is wrong here?

Thanks.