Can not add xsp:expr to xsl:attribute

[Simone Bortolaso]

Hi all, is there a way to jump across the following problem?    1)   <xsp:logic>  if(viewer.isPie()){    <tr><td bgcolor="#ffffff" width="340" height="20" vlign="bottom" align = "left" colspan = "2">    <img><xsl:attribute name = "src"> <xsl:value-of select="../report_information/piechart/@path"/><xsp:expr>viewer.getUnavailable()</xsp:expr>     </xsl:attribute></img>      </td></tr>  } </xsp:logic>     2) Alternatively, I try to define a xsl variable and assign it with in   <xsl:variable name = "param" ><xsp:expr>viewer.getUnavailable()</xsp:expr></xsl:variable>   <xsp:logic>  if(viewer.isPie()){    <tr><td bgcolor="#ffffff" width="340" height="20" vlign="bottom" align = "left" colspan = "2">    <img><xsl:attribute name = "src"> <xsl:value-of select="../report_information/piechart/@path"/><xsl:value-of select="{$param}">      </xsl:attribute></img>      </td></tr>  } </xsp:logic>   but it return the variable's name  end not its value.   Thank all in advance Simone.