Have you got your UCI? If not, then I am not sure how you are trying to link your paper application. If yes, then there are two ways to check the status:
1. You can log in to CIC ECAS, punch in your UCI, DOB, Country of Birth, Last name and track status.
2. If I am not wrong you are trying to link your application through GC_key, which is a tedious process in itself. You will have to use multiple permutation and combinations to see which combination of your credentials are able to search your application in the database. Please bear in mind, use spellings exactly what is mentioned on your passport (especially spaces). I can guarantee that if you follow these steps, you will be definitely able to link your application in GCKey, unless you have appointed a representative to your file, which you will have to withdraw in order to have your GCKey linked to your application.
Hope this helps.