If you have a Memo or VarChar in CR versions before v9, you will not be able to use it in a formula (except with IsNull) or for sorting, grouping or selecting. If you are not connecting via ODBC, but are using a native database driver, you may only see the first 255 characters of your field. A new KB article that gives 2 workarounds was posted by user RoadKill and is at the end.
The following explanation of the limitation is taken from a Seagate FAQ:
Crystal Reports does not currently support Memo fields in formulas or selection formulas. Because of this, you will not be able to browse data in Memo fields or reference Memo fields in formulas.
Crystal Reports reads database fields that meet any of these criteria as Memo fields: ?Fields exceeding 254 characters in length. ?Fields formatted as VarChar in the database (variable character length field). ?Fields formatted as Blob or Memo in the database.
NOTE One exception is the IsNull or NextIsNull functions. You can use Memo fields with these functions in a conditional formatting formula or a formula field. For more details on this, go to: