reportheading in reportheader

hi,

i am display my field in report header.

now this field has value in query like

item

item

item

so this is result in query. In ssrs i am putting this filed in report header,basically i just need to have 1 time item in header.

i dont knwo this will work.

but i am getting error like

Error    7    [rsInvalidAggregateScope] The Value expression for the text box ‘Reportingheading1’ has a scope parameter that is not valid for an aggregate function.  The scope parameter must be set to a string constant that is equal to either the name of a containing group, the name of a containing data region, or the name of a dataset.    

Anyidea?i need to put any aggregate function in expression?

addition  to this (alternate way) i am trying

I have a need to add a text box to a report in report header.. The text box will have an
 expression that I need to have that captues the value of a field from a
 second data set associated with the report. I add a text box but in the edit
 expresssion process I can't access any fields (from any data set) and i get
 the message Report item not linked to a dataset. I'm not trying to add a new
 table or anything like that. I just want to be able to grab that field value
 and display.

i am using something like this

= max(First(Fields!ReportHeading1.Value), "PortfolioInfo")

how to do this?

getting error under  Fields!ReportHeading1.Value , unknown collection member

Any idea?