for those who cannot access ECAS (but should be able to) - I heard about such cases:
1. Different country of birth. Someone was trying "Ukraine", but it turned out she had to use "USSR"
2. Date of birth, mixed Day and Month
If it could help, this work for me:
1. open
https://services3.cic.gc.ca/ecas/authenticate.do?app=
2. Accept conditions
3. in the "Identification Type:" drop down select "Client ID Number / ..."
4. Enter the number from PR Card, in XXXX-XXXX or XXXXXXXX format
5. In "Surname/Family Name:" text box enter your
last name.
6. Enter your date of birth in MM/DD/YYYY format. In some countries people use DD/MM/YYYY - here Month goes first, then Day!
7. Select "Place of birth" - the country you was born in, not the Country you have citizenship of.