I'd like the following loop to exit when there are no additional sheets
availble. Please help.

Do Until ActiveSheet.Next = False

Windows("Primary GBT Prod_Breakdown " & MyValue & ".xls").Activate
Selection.Copy
Windows("Agency Prime Gross Plotting by Placement " & MyValue &
".xls").Activate
Selection.PasteSpecial Paste:=xlValues, Operation:=xlNone, SkipBlanks:= _
False, Transpose:=False
Windows("Primary GBT Prod_Breakdown " & MyValue & ".xls").Activate
ActiveCell.Offset(22, 0).Range("A1").Select
Application.CutCopyMode = False
Selection.Copy
Windows("Agency Prime Gross Plotting by Placement " & MyValue &
".xls").Activate
ActiveCell.Offset(0, 1).Range("A1").Select
Selection.PasteSpecial Paste:=xlValues, Operation:=xlNone, SkipBlanks:= _
False, Transpose:=False
For b = 1 To 11
Windows("Primary GBT Prod_Breakdown " & MyValue & ".xls").Activate
ActiveCell.Offset(0, 1).Range("A1").Select
Application.CutCopyMode = False
Selection.Copy
Windows("Agency Prime Gross Plotting by Placement " & MyValue &
".xls").Activate
ActiveCell.Offset(-1, 2).Range("A1").Select
Selection.PasteSpecial Paste:=xlValues, Operation:=xlNone, SkipBlanks:= _
False, Transpose:=False
Next b
ActiveCell.Offset(64, -23).Range("A1").Select
Windows("Primary GBT Prod_Breakdown " & MyValue & ".xls").Activate
ActiveSheet.Next.Select

Loop