How to concatenate values in RDLC expression?

The following examples works for me:

=Fields!FirstName.Value & " " & Fields!LastName.Value

or

="$ " & Sum(Round((Fields!QTD_ORDER.Value - Fields!QTD_RETURN.Value) * Fields!PRICE.Value,2), "Entity_orderItens")

Have a look at MSDN

Check this : http://blogs.msdn.com/b/mosharaf/archive/2005/12/20/localreportcustomcode.aspx

it is possible to do in a different way in the rdlc report you can use VB code. Just click on the report with right mouse button. When the context menu from where you enter parameters go to Proprties. When clicking it you should see a tab control witch few tab pages. Go to tab page "Code" an there right you VB function it must be something like this

     Public Function concatestring(ByVal val1 As Object,ByVal val2 As Object,ByVal val3 As Object ) As String//         return val1 + ' ' + val2 + ' ' + val3 -- just string cocate in vb will do your task        End Function

Then call the function in your textbox like this

= Code.concatestring(Fields!MyField_1.Value,Fields!MyField_2.Value,Fields!MyField_3.Value )

P.S. I am not very sure if the VB code is working correctly just test it and if it is needed rewrite. If any other error occurs please post it to see what is the problem