wix - How to concat two variables at installlocation path -

i have problem on wix basic setup configuration. want install files programfiles/nameofcompany/nameofproduct. have following configuration now:

<?define productname="productname" ?> <?define manufacturer="companyname"?> <directory id="targetdir" name="sourcedir">   <directory id="programfilesfolder">     <directory id="installlocation" name="$(var.productname)">       <component id="productcomponent" guid="b11556a2-e066-4393-af5c-9c9210187eb2">         <file id='sampleappexe' name='sampleapp.exe' source='clipboardactivex.dll' vital='yes' />       </component>     </directory>   </directory> </directory> 

the problem got following error when try set folder1/folder2 @ installlocation directory entry:

the directory/@name attribute's value, 'folder1/folder2', not valid long name because contains illegal characters.  legal long names contain no more 260 characters , must contain @ least 1 non-period character.  character except follow may used: \ ? | > < : / * ". 

i want one:

<?define productname="productname" ?> <?define manufacturer="companyname"?> <directory id="targetdir" name="sourcedir">   <directory id="programfilesfolder">     <directory id="installlocation" name="$(var.manufacturer)\$(var.productname)">       <component id="productcomponent" guid="b11556a2-e066-4393-af5c-9c9210187eb2">         <file id='sampleappexe' name='sampleapp.exe' source='clipboardactivex.dll' vital='yes' />       </component>     </directory>   </directory> </directory> 

you must use nested directory elements nested directories. this:

... <directory id="programfilesfolder">     <directory id="manufacturer" name="$(var.manufacturer)">         <directory id="installlocation" name="$(var.productname)"> ...