Unexpected results for Max() function

[rjstacks]

Please forgive me, I'm very new to working with SQL and databases.

I'm writing a small application that interfaces with an MS database. My query is simply "SELECT MAX(order_num) AS \'maxorder\' FROM ORDERS"

But it doesn't return the correct order number. It should return 27, instead it returns 9.

This function should return the highest number in the data column, excluding blank data entries, shouldn't it?