Parameter`s Storage Type is not a string Area names from room names

[rinaldi.enrico_nhs]

I am trying to write parameters, names and another value from Rooms to Areas
I got this error Parameter`s Storage Type is not a string . I tried to cast into a String with the OOTB node but it did not work.

Any suggestions

[Sean_Fruin]

The issue is probably the “null” values.

[rinaldi.enrico_nhs]

Thanks< I solved with a Tiny python node as the nulls were not caught by the nulls nodes.