Skip a step in the Macro if a range has no data

Good afternoon,

This is my first post here, but I have relied upon this forum for solutions to several other problems. So, gratitude is due for your indirect help on prior issues. Now hopefully you can help me directly with my current issue.

I have a spreasheet and macro which takes bulk data, filters it and pastes it into different tabs based on category, and then subtotals that data before copying and pasting all of the subtotals onto another sheet. The problem I am having is that occasionally there is no data within a certain category, so the correponding sheet will be blank (except for headers). When the macro runs, I get a "run-time error '1004'" when it attempts to sub-total the data on the blank sheet. Is there a way to skip this step of the macro if there is no data within a certain sheet/range?

If it helps, here is the portion of VBA language where it hangs-up:

Sheets("Outsource AA").Select
    Columns("A:A").Select
    ActiveWorkbook.Worksheets("Outsource AA").Sort.SortFields.Clear
    ActiveWorkbook.Worksheets("Outsource AA").Sort.SortFields.Add Key:=Range("A1"), _
        SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
    With ActiveWorkbook.Worksheets("Outsource AA").Sort
        .SetRange Range("A2:I999")
        .Header = xlNo
        .MatchCase = False
        .Orientation = xlTopToBottom
        .SortMethod = xlPinYin
        .Apply
    End With
    Columns("B:B").Select
    Selection.Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
    Columns("A:A").Select
    Selection.TextToColumns Destination:=Range("A1"), DataType:=xlFixedWidth, _
        FieldInfo:=Array(Array(0, 4), Array(10, 1)), TrailingMinusNumbers:=True
    Range("A1").Select
    ActiveCell.FormulaR1C1 = "Date"
    Columns("A:A").Select
    With Selection
        .HorizontalAlignment = xlCenter
        .VerticalAlignment = xlBottom
        .WrapText = False
        .Orientation = 0
        .AddIndent = False
        .IndentLevel = 0
        .ShrinkToFit = False
        .ReadingOrder = xlContext
        .MergeCells = False
    End With
    Selection.ColumnWidth = 13
    Columns("B:B").Select
    Selection.Delete Shift:=xlToLeft
    Range("D13").Select
    ActiveWindow.SmallScroll Down:=-15
    Columns("A:A").Select
    Selection.Subtotal GroupBy:=1, Function:=xlCount, TotalList:=Array(1), _
        Replace:=True, PageBreaks:=False, SummaryBelowData:=False    
    Range("C13").Select
    Columns("B:B").Select
    Selection.Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
        Columns("A:A").Select
    Selection.TextToColumns Destination:=Range("A1"), DataType:=xlFixedWidth, _
        FieldInfo:=Array(Array(0, 2), Array(9, 1)), TrailingMinusNumbers:=True
    Columns("B:B").Select
    Selection.Delete Shift:=xlToLeft