unix shell command with slightly complicated commands

Hi,

 I am trying to use a 'grep' command from RTLCompile to detect a certain pattern in a generated file, and based on the outcome of the grep, do something. To be more precise, I am trying to do the following:

  1) First generate a report fiile: 

           report cdn_loop_breaker > loops.txt

   2) then trying to grep that file if the tool detected any loop or not by using a unix shell command:

           grep "No loop" loops.txt

       when I try to do this unix command from rc prompt, 

            shell grep "No loop" combinational_loops.txt

       it fails to perform the grep saying "Child process exited abnormally". Looks like, it cannot interpret two words "No loop".

       However, if I specify one word it can match the string properly. 

Any idea how I can do this? 

Thanks.