sql else statement

1) Please describe what you are trying to do

2) Please post the whole SQL statement so we can get the context

I am trying to check for a null value in a date field, so if there is a null I can send back an 'N/A'. The code below now runs, but I get
Server: Msg 241, Level 16, State 1, Line 27
Syntax error converting datetime from character string.

                  (SELECT TOP 1 esDate FROM dbo.lpAssignDetails
                        WHERE planVersion = @intPlanversion AND planID = @intplanID and planFinished = 0 or planFinished = 1 AND userID = dbo.candidates.candidateID ORDER BY esDate) AS 'Invite Date',
                  CASE WHEN lps.lpSignDateTime IS NOT NULL THEN
                        (SELECT TOP 1 lpSignDateTime FROM dbo.lpSign
                              WHERE planVersion = @intPlanversion AND planID = @intplanID AND userID = dbo.candidates.candidateID)
                        else 'N/A'
                         END 'Date Trained'
            FROM         dbo.candidates

(SELECT TOP 1 esDate FROM dbo.lpAssignDetails
 WHERE planVersion = @intPlanversion AND planID = @intplanID and planFinished = 0 or planFinished = 1 AND userID = dbo.candidates.candidateID ORDER BY esDate) AS InviteDate,
 CASE WHEN NOT lps.lpSignDateTime IS NULL THEN
 (SELECT TOP 1 lpSignDateTime FROM dbo.lpSign
 WHERE planVersion = @intPlanversion AND planID = @intplanID AND userID = dbo.candidates.candidateID) AS InviteDate
 else 'N/A' AS InviteDate
 END, [Date Trained]
 FROM dbo.candidates

Table or Field Alias must not be in single quotation marks and must not contain spaces (AS InviteDate instead of AS 'Invite Date'). You forgot the "AS InviteDate" on the second SELECT and 'N/A'.

You can also try "AS [Invite Date]" if you want to keep the space in field name. Use the brackets [] instead of single quotation marks.

Also I think you have to use "NOT lps.lpSignDateTime IS NULL" instead of "lps.lpSignDateTime IS NOT NULL".

What is 'Date Trained'? Is this another field of the table? Then you have to use this:  ...END, [Date Trained] FROM...

Cheers