[Zope] Problems with Computed Fields

Hello, I want to use a computed field to convert the broken umlauts from a database. I added a computed field and tried the following expression: translate(ARTBEZ,maketrans('”„','öüä')) But when i test the expression i get the following result: Test Computed Field Expression: translate(ARTBEZ,maketrans('”„','öüä')) Computed Field Error: (, ) Does anybody have a solution for my problem? Bye, Alex