Custom validation rule + array

[eluser]sqwk[/eluser]
When I am passing aan array (from a multi select) to a custom validation rule via callback_, the rule doesn't receive the array, but rather all the nodes separated by nothing.

Running a var_dump inside the validation rule produces something like this:

Code:

string(1) "1" string(1) "3"

How can I pass the array to the validation rule? (To count nodes etc.)