What is wrong with this code?

<p><script type=text/vbscript language=vbscript>
        set objnet=createobject("ADSystemInfo")
        set struser=objnet.username
        set count1=1
        do until right(struser,1)=chr(44)
          set strname=left(struser,count1)
          count1 = count1+1
        loop
        document.write("Welcome " + strname)
        </script></p>
When I take out the loop stuff and do document.write("Welcome " + objnet.username) the distinquished name shows on my page but when the above code is added nothing shows at the top of my page.

seeker55