how to set xforms:variable value to xforms:value tag in checkbox?

Hi All,

I am not able to set temp1 variable to  <xforms:value ref="$temp1"/> in chech box component .
 
Please help me how  to set temp1 variable value ,to ref attribute of xforms:value tag.
 
 
 My code shown below: 
<xforms:repeat nodeset="instance('template-instance')//record">
  <xxforms:variable name="temp" select="title"/>
  <xxforms:variable name="temp1" select='substring-after(substring-after(substring-after(title,"/"),"/"),"/")'/>
    
 <xforms:select ref="instance('main-instance')/checkbox" appearance="full" multiple="true" style="font-size: 10pt">
  <xforms:choices>
       <xforms:item>
                 <xforms:label></xforms:label>
                 <xforms:value ref="$temp1"/>
        </xforms:item>
  </xforms:choices>
 </xforms:select>
</xforms:repeat> 

 

Regards,

laxmi.