Can anyone help with the below error, Error: Incorrect number of parameters for function 'ISBLANK()'. Expected 1, received 2

Question

AND ( 
ISPICKVAL( VALIDATED__c, "YES" ), 
OR (  
ISPICKVAL( Account_Loss_Machine_Loss__c , " "), 
ISPICKVAL( Lost_To__c , " "), 
ISPICKVAL( Reason_For_Loss__c , " ") ,
ISPICKVAL( Written_Notice_Given__c ,  " ") ,
ISBLANK( Model__c , " ") ,
ISBLANK( Number_od_Devices__c , " ") ,
ISBLANK( Serial_Number__c ,  " ") ,
ISBLANK( Contract_End_Date__c ,  " ") ,
ISPICKVAL( Settlement_Paid__c ,  " ") ,
ISPICKVAL( Machine_Returned_To__c ,  " ") ,
ISPICKVAL( Collection_Required__c ,  " ") ,
ISBLANK( Collection_Date__c ,  " ") ,
ISBLANK( Collection_Charge_Agreed__c ,  " ") ,
ISPICKVAL(   Account_Closed_On_SA__c  ,  " ") ,
ISPICKVAL(  Inventory_Removed__c ,  " ") ,
ISBLANK( Last_Known_CCR__c ,  " ") ,
ISPICKVAL( Loss_Customer_Questionnaire_Sent__c ,  " ") ,
ISPICKVAL( Questionnaire_Received_Back__c ,  " " )


))

Answer 1

the ISBLANK() function accepts only a single parameter and returns the TRUE or FALSE value, it just needs the field which you are interested into. Your code should be changed this way:

AND ( 
ISPICKVAL( VALIDATED__c, "YES" ), 
OR (  
ISPICKVAL( Account_Loss_Machine_Loss__c , " "), 
ISPICKVAL( Lost_To__c , " "), 
ISPICKVAL( Reason_For_Loss__c , " ") ,
ISPICKVAL( Written_Notice_Given__c ,  " ") ,
ISBLANK( Model__c ) ,
ISBLANK( Number_od_Devices__c ) ,
ISBLANK( Serial_Number__c ) ,
ISBLANK( Contract_End_Date__c ) ,
ISPICKVAL( Settlement_Paid__c ,  " ") ,
ISPICKVAL( Machine_Returned_To__c ,  " ") ,
ISPICKVAL( Collection_Required__c ,  " ") ,
ISBLANK( Collection_Date__c ) ,
ISBLANK( Collection_Charge_Agreed__c ) ,
ISPICKVAL(   Account_Closed_On_SA__c  ,  " ") ,
ISPICKVAL(  Inventory_Removed__c ,  " ") ,
ISBLANK( Last_Known_CCR__c ) ,
ISPICKVAL( Loss_Customer_Questionnaire_Sent__c ,  " ") ,
ISPICKVAL( Questionnaire_Received_Back__c ,  " " )

))