How to update data in an Access Table in the sequence of the source table/query?

I have the source table in Record number and tag number sequence.    
EX.  Rec#       Tag Num   Count
         1              100             25
         2              100             35
         3               100            199
         4                101            44
         5                101            202
         6                101            34

The table I want to update is
      tagNum      Ucount
         100              25
         101              202
 The table to be updated only had the tag number and the count number to be updated.      I am getting the update to run in random sequence and I need it to run in the sequence of the source table.    I want the ucount to be the count from the highest Rec# and the Tag# number that matches.    
I wanted the results to be        TagNum    Ucount
                                                          100           199
                                                           101           34

How to I stop it from updating in a random sequence?     I tried building the source in the sequence I wanted it to update the update table but got similar results.   Any suggestions?
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Rey Obrero (Capricorn1)Commented:
the easiest way to do this is run a make table query

SELECT Max(TX.[Rec#]) AS [MaxOfRec#], TX.[Tag Num], Last(TX.Count) AS LastOfCount INTO TZ
GROUP BY TX.[Tag Num];

then run an update query

UPDATE TU INNER JOIN TZ ON TU.TagNum = TZ.[Tag Num] SET TU.UCount = [TZ].[LastOfCount];

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