Blank() causes an error in an if() - PowerApps

I am trying to filter a table from Dynamics 365 by selecting a radio button which will update the table on the screen.

The user has three options to choose from: "School", "Business", "All".

When the user selects "All" then it should look in the "Accounts" table and search the "industrycode" column for blank values.

Below is a working Filter(), which returns the result I want

Filter(Accounts,industrycode = Blank())

However if I add an If() statement to it determine which value the user selected from the radio, I get an error that says the '=' symbol is an invalid argument type.

Filter(Accounts,industrycode = If("All" in radio_cust_type.Selected.Value,Blank()))