Why does this formula not work?

Why does this formula not work?

I have a simple formula that is triggering as true, even when it is not. 

if(Due_Date != null && Status!="Repeat")
{
input.Status = "In Progress";
}

In that formula (my interpretation), if the date is not blank and the status is not Repeat, then change status to In Progress.  However, it is still firing when the status is Repeat and changing the status to In Progress.  

I think it has something to do with the date field.  Really not sure why it isn't working at expected

Any help? 

Thanks
Michael Custer