A calculated field only populates on record save, so if this is a new calculated field and the record has not been edited since then the field will not populate. If you do an edit/save on the record it will trigger the calculation.
If this is not the case then to resolve this issue Support will need to review the formula being used to populate the field. Therefore please see the following Get support in Access CRM and reference the title of this article and please include details of the field affected.
