VBA Looping/Logic Issue - string

Question

I am writing a macro in excel for work and I am having trouble. In this scenario there are two sheets, "BU" and "TOPS Information". When the macro is used it is supposed to search every line of "BU" for the value found in "TOPS Information", then go to the next line of "TOPS Information and repeat the process. If it finds a correct match it is supposed to copy a cell and paste it into "TOPS Information".
Here is the code:
Sub QIM()
Dim j As Integer
Dim k As Integer
Dim i As Integer
Dim l As Integer
Dim m As Integer
Dim searchArray(1 To 3) As String
j = 0
k = 1
'WARNING: Temporary Sheet Names
lastRowTOPS = Worksheets("TOPS Information").Cells(Rows.Count, "A").End(xlUp).Row
lastRowBU = Worksheets("BU").Cells(Rows.Count, "A").End(xlUp).Row
'Cycle through BU rows
For j = lastRowTOPS To 1 Step -1
'Cycle through searchArray for each BU row
For k = lastRowBU To 1 Step -1
'//////////////////////////////////////
x = Sheets("BU").Range("B" & k).Value
y = Range("C" & j).Value
If StrComp(x, y) = 1 Then
Sheets("BU").Range("C" & k).Copy
Range("H" & j).PasteSpecial
End If
'//////////////////////////////////////
Next k
Next j
End Sub
This Macro obviously only works if "TOPS Information" is selected at the time. Any and all help would be most appreciated. THANKS!

Answer 1

You sorta answered it yourself. Range refers to the current sheet, but when you're bouncing around then you have to qualify it.
Prefix your ranges with the appropriate sheet like so,
Sub QIM()
Dim j As Integer
Dim k As Integer
Dim i As Integer
Dim l As Integer
Dim m As Integer
Dim searchArray(1 To 3) As String
j = 0
k = 1
'WARNING: Temporary Sheet Names
lastRowTOPS = Worksheets("TOPS Information").Cells(Rows.Count, "A").End(xlUp).Row
lastRowBU = Worksheets("BU").Cells(Rows.Count, "A").End(xlUp).Row
'Cycle through BU rows
For j = lastRowTOPS To 1 Step -1
'Cycle through searchArray for each BU row
For k = lastRowBU To 1 Step -1
'//////////////////////////////////////
x = Sheets("BU").Range("B" & k).Value
y = Sheets("TOPS Information").Range("C" & j).Value
If StrComp(x, y) = 1 Then
Sheets("BU").Range("C" & k).Copy
Sheets("TOPS Information").Range("H" & j).PasteSpecial
End If
'//////////////////////////////////////
Next k
Next j
End Sub

Answer 2

Assuming only want to copy the top most found data in BU to TOPS, you can use below.
Sub QIM()
Dim oWS_TOPS As Worksheet, oWS_BU As Worksheet ' Worksheet objects
Dim oRng_TOPS As Range, oRng_BU As Range ' Range objects
Dim R_TOPS As Long, R_BU As Long
Set oWS_TOPS = ThisWorkbook.Worksheets("TOPS Information") ' <-- Replace this "TOPS Information" to match future changes
Set oWS_BU = ThisWorkbook.Worksheets("BU") ' <-- Replace this "BU" to match future changes
R_TOPS = oWS_TOPS.Cells(Rows.Count, "A").End(xlUp).Row
R_BU = oWS_BU.Cells(Rows.Count, "A").End(xlUp).Row
' Search column B of BU for each cell in column C of TOPS
For Each oRng_TOPS In oWS_TOPS.Columns("C").Cells ' <-- Replace this "C" to match future changes
' Exit if row is more than last A column data
If oRng_TOPS.Row > R_TOPS Then Exit For
For Each oRng_BU In oWS_BU.Columns("B").Cells ' <-- Replace this "B" to match future changes
' Exit if row is more than last A column data
If oRng_BU.Row > R_BU Then Exit For
' Check if Ranges match (## See Update ##)
If InStr(1, oRng_TOPS.Value, oRng_BU.Value, vbTextCompare) > 0 Then
' Copy column C of found row in BU to column H of TOPS, then exit
oWS_BU.Cells(oRng_BU.Row, "C").Copy oWS_TOPS.Cells(oRng_TOPS.Row, "H") ' <-- Replace these "C" and "H" to match future changes
Exit For
End If
Next
Next
Set oWS_TOPS = Nothing
Set oWS_BU = Nothing
End Sub
There are many ways to achieve your goal, and this is one of it.
UPDATE Note on comparing cell values (String):
StrComp(S1,S2[,mode]) only return 3 values {-1, 0, 1} to indicate if S1 is less/equal/greater than S2. If you want an exact match (case sensitive and exact spacing), use If StrComp(S1,S2) = 0 Then.
InStr([i,]S1,S2[,mode]) only returns positive values - it returns the character location of first appearance of S2 in S1. If S2 is not found then it returns zero.
You can also use Trim(sText) to remove leading/ending spaces of sText.
Hope below screenshot says more.