Inconsistent registry

[Davide Liessi]

Dear all,
I suspect that my MacPorts registry is in an inconsistent state:

$ port installed name:carp
The following ports are currently installed:
  p5.26-carp-clan @6.70.0_0 (active)
$ port rdependents p5.26-carp-clean
Error: Registry error: p5.26-carp-clean not registered as installed.

I always used the port command and I have never directly manipulated
the registry.
How could it happen?
Is uninstalling and reinstalling MacPorts and all ports the only solution?

Best wishes.
Davide