Problem changing validation on an adjoining cell via selection_change

[NewOrderFac33]

Good morning - just wondering if anyone can help.

I'm attempting to set up a project planning database that will contain a number of sub tasks that will be performed by a named person in a named team.

The idea is that when a team is selected from a drop down list, the adjoing cell's validation will change so that it only contains a drop down list containing members of that specific team.

Each team's members are contained in a specific named range and the whole thing is packaged in worksheet_selectionchange - this idea is that when you change the team, the change is picked up and the adjoing cell will then contain a drop down comprising the named range for that team.

The problem that I have is that I keep getting the following message when Ii change the entry in the "Team" column:

Runtime error -2147417848 (80010108)
Automation error
The object invoked has disconnected from its clients

The funny thing is, that when I click "End", the result is exactly what I wanted - the validation in the adjoining cell correctly reflects the change in the Team Name.

What's going on?

here's a section of the Worksheet_Change code

 Case Is = "Analysis"
                    MsgBox ("Analysis")
                    Target.Offset(0, -4).Resize(1, 17).Interior.ColorIndex = 40 
                    Target.Offset(0, -4).Resize(1, 17).Font.ColorIndex = 1 
                    Target.Offset(0, 1).Select
                    With Selection.Validation
                       .Delete
                       .Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:=xlBetween, Formula1:="=Analysis"
                       .IgnoreBlank = True
                       .InCellDropdown = True
                       .InputTitle = ""
                       .ErrorTitle = ""
                       .InputMessage = ""
                       .ErrorMessage = ""
                       .ShowInput = True
                       .ShowError = False
                    End With

Originally, instead of

Target.Offset(0, 1).Select
With Selection.Validation

I had

with  target.Offset(0, 1)

I tried the select to see if the problem lay with setting validation against a target offset, but the results are the same.

This is driving me nuts - any assistance gratefully accepted!