App needs to exec script

I need for an app to exec a script. The script I'm testing with is simply mkdir /sdcard/test.dir, and works when directly called. The code compiles and executes, but the script isn't being run. My coding environment is Ubuntu 10.04, Sun JDK 6, Android & vi. No Eclipse.

Thanks in advance. This supposedly simple function has me stumped.

Code:

---

public void execCommandLine1()

    {
        try
        {
            Runtime rt = Runtime.getRuntime();
            Process proc = rt.exec("sh /system/xbin/test.sh");  // tried with sh and w/o
            InputStream is = proc.getInputStream();
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            String line;
            prompt.setText("default pressed");

      while ((line = br.readLine()) != null) {
        System.out.println(line);
      }
          } catch (Throwable t)
          {
            t.printStackTrace();
          }

}

---