I am trying to write a report that returns the names which have blank records against them for Appraisal.  I can get all the records with appraisal records but when using If isnull({tbl.field}) then "--blank--" else {tbl.field}  I keep getting asked for a boolean at the end and don't know what it wants?

Thank you for replying but I have reached the end of my knowledge and tether with this, I thought a boolean was a true or false statement but it won't accept this, the help desk have now said that it is something to do with the links in my table selection and gone away to work it out, probably won't hear from them again!  Anyway this is what I have so far  .....  If isnull({Competency_Appraisal_History.Appraisal Number}) then "--blank--" else ..........not sure what to do next?