Null value field validation failing

Can anybody let me know how to validate the below field (tr_part) highlighted to blank. File is pipe delimited (|) with text in doubt quotes

Flat File

Below validation rule is able to reject the second row (highlighted in Green), however I want to reject the 3^rd line (highlighted in red) also.

Is there any way to check the field is blank and reject the record , I have tried to get the length of the field and validate but that doesn't worked.

Any help on this will be appreciated.