First, make sure that the customization of the report is correct:
When you view the report in question, make sure that you are viewing All Customers, assuming you want this report to generate for all customers. To do so, right-click on the name of the report, select Customize, and if the particular report in question has a Transactions tab, go there and specify All Customers. Also, if the report you are running has a Date tab, make sure that the date specified is what you want. Similarly, if you want to generate the report for just one customer, right-click on the name of the report, select Customize, and if there is a Transactions tab, go there and specify the one customer for whom you want to report.
If the above is correct and still customers names are not appearing on reports, try running the "MDIE55RP.EXE" from the link below.
MDIE55RP.EXE