This is just FYI: I got this problem resolved by setting all the pivotitems values to true using 'For each' statemen
and then using another 'for each' statment , set all pivotitems visible property to true except the specific item for that use
login id
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On Error Resume Nex
With pt.PivotFields("Series"
pf.AutoSort xlManual, pf.SourceNam
For Each pi In pf.PivotItem
pi.Visible = Tru

Next p
pf.AutoSort xlAscending, pf.SourceNam
End Wit

On Error Resume Nex
With pt.PivotFields("Series"
pf.AutoSort xlManual, pf.SourceNam
For Each pi In pf.PivotItem
pi.Visible = Fals
If pi.Value = uname The
pi.Visible = Tru
End I
Next p
pf.AutoSort xlAscending, pf.SourceNam
End Wit
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