If Statement with multiple conditions

I have a spreadsheet that basically has 3 columns “ Due Date” , “Date Paid” and “Paid”, depending on what is entered in the “Date Paid” column a statement will display in the “Paid” column. Need to mention that the due date will always be a fixed date such as 31 May 20XX. This is what I need it to do;

- If a date is entered in the ‘Date Paid” col, the “Paid” Col will display “Paid”. No matter what the date entered is, could be any date between now and 31 May 2011..

- If nothing is entered in the “Date Paid” col and it is before 30 days of the due date, the “Paid” col will display Due.

- If nothing is entered in the “Date Paid” col and it is within 30 days of the of the “Due Date” the “Paid” col will display “Warning”.

- If nothing is entered in the “Date Paid col and it is after the “Due Date”, the “Paid” col will display “Overdue”

This is the formula I have come up with,
=IF((TODAY()+30)<J2,"",IF(TODAY()>J2,"Overdue",IF( ISBLANK(I2),"Warning",K2*1)))

Everything works except if I enter a date in the “Date Paid” col nothing appears in the “Paid” col until it is within 30 days of the due date.

If this has to be a VBA, I am good with that, just not sure on how to write it, maybe a loop statement.

Any help is greatly appreciated