Cannot upload assignment

Hi!, I have a simple problem when using assignments.

The problem is that when I create an assignment using the simple option or the advance uploading option, the result is the same, the button to upload a file it does not appear at all.

I went to check out permissions for students regarding the assigments and I checked to "Allow" for both Submit and View just in case,.. but nothing has changed.

I attach two images  to  show what happens.

Thank you for the time and interest.

Mercedes Delgado