Concatenate date error

[que1983]

min([Business].[RISK MANAGEMENT].[LOCK EXPIRATION DATE])+' '+max([Business].[RISK MANAGEMENT].[LOCK EXPIRATION DATE])

This dataitem shows the above in the expressions area.  I validated it and it produced not errors.  However when I add the data item to a chart I created it generates RQP-DEF-0177 An error occurred while performing operation 'sqlPrepareWithOptions' status='-69'.  the details say is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.RSV-SRV-0042   Usually this occurs when you have two of different data types.  However these are the same data type.  I even tried this in another query and get the same error.  How do you concatenate dates???

[the6campbells]

If your colums are DATE types then you must CAST( ) them to a character type