My photo is not accepted by the system.

First and foremost, the photo should be of high quality, the background has to be smooth, preferably  white, but definitely with a good contrast and distinct face features. The face has to be directed straight at the camera lens, the head cannot be skewed and should be visible in full.
A photo in format is preferred in minimum size of 1000 x 1250 pixels, although the system would accept 500x625 pixels size, but the cropping won’t be possible in the result of which the face on the photo will be too small to meet the requirements.