Hello to you both, kimmwhali and xCami:
I had the same trouble like you initially. I tried linking my account even before we have yet to received an App number. On 5 January, the day we got AOR1, I tried again using both UCI, App number and the choices in the drop-down menu of App no./Family Name, etc. I still kept being rejected until I got the message to try again after 24 hours. Yep, quite frustrating. However, just few minutes passed and I tried again (it said to wait 24 hours, right?). For some reason (program glitch, maybe?), all the boxes to fill in were up so I continued

At this time, I tried again the < Family Name / Given Name / Birthday > ----- Voila, it worked!
I just thought that maybe the reason why, even though I tried all kinds of tricks and it was still not successful, I noticed though that when we received the AOR1, my name showing does not include my Middle Name. What I have been doing initially was I keep on adding my Middle Name as part of the Given Name because that's how I filled my application forms. But upon noticing how CIC uses my name, I followed it on my last try of linking the app to MyCIC, to which on the Given Name, I did not include anymore my Middle Name. In my country, Middle Name is in fact a Maiden Name. When filling CIC's form and asking for name as exactly shown on the passport, I was at first confused because there is no mention of Middle Name. I later realized that Canada takes Middle Name as part of Given Name so that's what I did.
Nweis, don't lose hope. You will still get your Apps linked to MyCIC. Yes, it's the same below steps that I followed:
1. Logged in with GC Key account.
2. Permanent Residence > Family Class (Spouses)
2-a. Application Number and Family Name - Copy/pasted application number from email (including the F) and entered PA's last name.
3. City of Birth - I entered 1 space (hit spacebar once)
4. Country of Birth - Selected PA's country of birth
5. Passport Info - Did not enter any passport info
6. Other Application Info - Filled out the other application info as per our application and put '2' as the number of members in the application. I am sponsoring my husband, no dependents.
Again, for 2-a, I selected Family Name, Given Name, Birthday (This is Principal Applicant's (PA) info). On no. 6, I entered '4' because I have 2 dependents.
Btw, I am the Principal Applicant
Good luck! Sorry for the long note.