Self Join Using Instead Of Update Trigger On A View

Hello all...I'd appreciate any help on this one.

I created a View...the view looks at four seperate tables.

Next, I created an Instead of Update trigger on that view. It works fine...for a regular UPDATE...SET.

However, it throws an error when I try an update and self join based on that view:

Update T1
Set RateUsed = T1.RateUsed
From Taxroll..Taxroll T1 Join
Taxroll..Taxroll T2 on
T1.Asmt = T2.Asmt and
T1.Taxyear = T2.Taxyear
Where T1.Asmt = '123456789012'
And T1.Taxyear = 2007
And T2.RollChgNum = ''
And T1.RollChgNum Like '%X'
And IsNull(T1.RateUsed,'') > ''

Msg 414, Level 16, State 1, Line 2
UPDATE is not allowed because the statement updates view "Taxroll..Taxroll" which participates in a join and has an INSTEAD OF UPDATE trigger.

There are a few caveats:
First, I thought the join issue was in the view itself. I re-created the view using no joins...all subqueries and still get the error. Second, I re-created the Instead of Update Trigger with no joins, and still get the error.

Thanks!