Comparing dates from two different tables in a related table

I have three tables:

1. - Expected Date

2. Ship Date

3. Order Table

The order table has relationships with the Expected Date Calendar table and the Ship Date Table. I've put the columns I need in a matrix.

I am wanting to compare the Due Date (in WVL) column to the Ship Date column. If the Due Date column is > than the Ship Date Column, Not ok, OK.

It SEEMS like it would be a simple IF function - but it won't reference the columns properly. I've tried using the RELATED function - says it needs to be a fully qualified column. Any ideas of how to make this work properly?

Thanks in advance! 

NOTE: the relationship between the orders table and the two different dates table - is based off a date id for each table. the orders table has a shipdateid column and a expecteddateid column. Many to one, I believe.