Priorvalue is not Exported then not allowed to change status to delivered

Question

The below code is mentioned in formula editor and this is showing

The formula expression is invalid: Incorrect number of parameters for function 'PRIORVALUE()'. Expected 1, received 2

  PRIORVALUE(([Opportunity].Status__c ), "Exported"))

Answer 1

The correct syntax for using prior value for picklist fields is-

ISPICKVAL(PRIORVALUE(Field), 'Value')

Update your formula as given below-

ISPICKVAL(PRIORVALUE(Opportunity.Status__c), 'Exported')

Answer 2

As mentioned in the Error You have one Extra ) at the end . Can you try this.

  PRIORVALUE(([Opportunity].Status__c ), "Exported")

If Status is picklist field then you have to use ISPICKVAL() function as well like below.

 ISPICKVAL( PRIORVALUE([Opportunity].Status__c), 'Exported')

As per the updated question your if current values is Exported then only you should be able to change it to Delivered.

Which means the validation should be as below.

AND(ISPICKVAL(Opportunity.Status__c,'Delivered'), NOT( ISPICKVAL( PRIORVALUE(Opportunity.Status__c), 'Exported')))

This check if we are changing Status to Delivered and prior value is not Exported it shows the Error