How do I create a conditional column by comparing data from two existing columns?

I am new to Power Query and using Power Query to pull data in from an external file.  The data has multiple columns. The two columns, Date and Mine, are the ones that I want to use to create a new conditional column from.  The value for Mine needs to be changed for one value based on whether it is before or after a certain date.

An example of the table looks like this

I tried the following to create a new column that I would then use to replace the Existing "Mine" column:

= Table.AddColumn(#"Removed Columns", "Mine1", each if [Mine] <> "OBO" then [Mine] else if [Mine] = "OBO" and [Date] < 01/04/2024 then "OBC" else "OBO")

However the code above produces an Expression.Error

Expression.Error: We cannot apply operator < to types Number and Date.

Details:

    Operator=<

    Left=0.001482213

    Right=1/05/2024

I am hoping I just have a syntax error but any help is much appreciated.