Using ISBLANK with text

I have what seems to be a simple SharePoint validation to validate If Priority=”Urgent Business Need” then Justification cannot be blank. I can get it work fine in Excel but it does not work in SharePoint.

I have tried using multiple permutations of an IF statement and cannot get it to work.

=IF([Priority]=”Urgent Business Need”,IF(NOT(ISBLANK([Justification])),TRUE,FALSE)

I have also tried using an AND statement instead with no success.

"=AND([Priority]="Urgent Business Need",NOT(ISBLANK([Justification])))"

I will be greatly appreciative for any help :)