Summaries containing string

[workinprogress]

Hi all,
I am using Crystal Reports 2011. I would like to summarize a formula field. The summary's output could be a number normally, but a string as output if certain conditions occur.

e.g.

If Sum({InvalidNumberCheck}) = -99999 Then
    "error"
Else
    ToText(Sum({InvalidNumberCheck}))

where "InvalidNumberCheck" is a formula field correctly defined (also added to the report). When attempting  to save the formula I am prompted with the popup "The field name is not known"

Thanks and regards

[ido_millet · Accepted solution]

Given that InvalidNumberCheck is a formula, you should refer to it as {@InvalidNumberCheck} rather than  {InvalidNumberCheck}

Better yet, use the formula editor to navigate and insert it into the formula expression, instead of trying to type it yourself.