Do you mean that the Cardfile shows the number of record cards, but does not display the contents of each card?
I have had an intermittent problem with card contents not being displayed, but usually this is cleared by closing Sidekick and restarting it. Have you tried closing the cardfile and reopening it, or possibly another cardfile, to see if that clears the problem?
Which version of Windows are you running Sidekick under?
As a last resort you may need to reload Sidekick, but backup all your data first.