Programatically Show Hide Report Members?

Does anyone know how to programatically show hide members (specificallytextboxes) in a report based on whether another field is Null orEmpty? I have tried to do something to the effect of
<code>
Sub ShowBox()
If Len(Fields!itm.Formula.Value)>0 Then
Fields!textbox30.Visibility = True
End If
End Sub
</code>
I put this in the code section under report properties but I get an error to the effect of
References to a non-shared member require an object reference
and
Expression does not produce a value
I know i am doing this totally wrong, can someone help me out?

thanks

in the textbox expression you can do something like :

=IIF(Len(Fields!itm.Formula.Value)>0, Fields!itm.Formula.Value, "")

|||

ndinakar wrote:

in the textbox expression you can do something like :

=IIF(Len(Fields!itm.Formula.Value)>0, Fields!itm.Formula.Value, "")

Just wondering if any one got any more ideas:
I tried this way:

=IIF((Fields!group1.Value)=Group2,Fields!Isuue.Value,

Fields!Name.Value = False) does not work.(By the way, Issue is a varchar field)

The exception is thrown saying

Microsoft.ReportingServices.ReportProcessing.ReportProcessingException

=IIF((Fields!group1.Value)=Group2,Fields!Issue.Value,

Fields!Name.Value = "") doesn't give any error but doesn't work properly.

It shows the column, doesn't hide it.

Even if it hides the coulmn it doesn't delete the space for that column because

there are already some items in that column as shown below

Group1

Name Issue Marks

ss sds 90

gss pds 90

Group2

Name Marks

ss 90

gss 90

Marks Column should be printed in the place of Issue column under group2. Is that possible