Validating the Assignment DFF based on the Person type is erroring out in all the scenarios

Summary:

Unable to validate the Assignment DFF based on person type, which is erroring out in both positive and negative scenarios.

Content (required):

We are trying to make the the DFF (LOV) mandatory on Assignment page based on the Person Type (Ex: employee). When Person type is employee, the value in the DFF should not be Null. If it is null it should throw an error and once the value is selected it should allow user to the next region but we are getting the error in both the scenarios. (Attached the Rule screenshot we have created).

Rule type: Object Validation Rule Type