I am trying to create a checke for my web application but when i try to run it, its giving an error. Can any one help me with this.

I have a web application of flight reservation and when i issue the ticket it opens a new pop up window of my application where it has the ticket information. In the keyword view i am selecting the actual page where i need to create the checkpoint it does show in the key word view but it gives an error. I have tried standard checkpoint and text checkpoint. I just right click and select the whole text i want to create a checkpoint but no luck. any ideas please..