There are three things involve why applicants get invalid login Error while trying to take their Assessment Test on the portal.
These three (3) things are:
1. You tried to take test ahead of the schedule date for your selected programme
2. You did not receive N-Power Invitation SMS.
3. May be your BVN record did not match with your application
Before applicants are allowed to take test, their application information are verify by N-Power to attest the authenticity and if confirm accurate then your profile will be configure and grant access to write the test.View also=>N-Power Assessment Test Timetable (Soft Copy)
However do not wait for SMS when it get to your schedule date for Assessment Test and you didn't get any. Sometimes it may not get to you because of Network congestion. Login and write the test.
According to N-Power Every Applicant will get an SMS to either Proceed to the testing stage or end their application Journey for 2017 so if you haven't gotten an SMS Please be patient you will get one.
Remember N-Tax Assessment continue so if you are an NTax Applicant and you miss your test schedule date, go login and write your test.