This could be because:
- The student is not enrolled in the assessment (either accidentally or on purpose)
- The student was not enrolled in the assessment in the time period the report card is reflecting
Check this within the assessment setup in Students > Assessments > Assessment Policy > Manage Assessments and select the relevant assessment.
Make sure the students are added to the assessment.
Check this in the Report Card setup in Students > Report Cards.
Firstly look at the general settings on the Report Card - was the student enrolled in the course on or before the report card date?
Secondly, navigate to the attainment tab and check the date range set for assessment grade capture. Has the student been enrolled into the assessment within the time frame set and have they had any marks entered?