You have the operators right, but your examples and the names of your fields suggest a data type issue.
Window1datecalc, windowdate2datecalc and timestamp should all be fields of the same data type. They should all be of type date or all be of type timestamp.
Your example info suggests that Date would make more sense than TimeStamp as the data type.
That was it! The data from survey 1 was pulled in from a CSV, so I think Filemaker was treating the timestamp variable as text. I just extracted the text from the timestamp and created a new date field using text functions. Thanks for the help.