Find list of words from a range if words exits multiple times - excel

Question

I have a list of words in Sheet1 I need to match one by one from Sheets("Sheet2").Range("A1:A7500") until the end of the Range. Whenever word is matched I need to do something with it in Sheet1. That word occurs multiple times in Sheets("Sheet2").Range("A1:A7500").
Following code is Finding word only once. I dont understand where it is going wrong.
Sub XMAX()
Dim lrow As Long
Dim cel As Range
Dim oRng As Range: Set oRng = Sheets("Sheet2").Range("A1:A7500")
Dim oFoundRng As Range, oLastRng As Range
lrow = Sheets("sheet1").Cells(Sheets("Sheet1").Rows.Count, "f").End(xlUp).Row
'''''''''''''''Sheet1'''''''''''''''
For Each cel In Range("f4:f" & lrow)
If IsEmpty(cel.Value) = False Then
Set oFoundRng = oRng.find(cel.Value)
Do While Not oFoundRng Is Nothing
If UCase(oFoundRng.Offset(0, 1).Value) = "ISAAC" Then
Range("X" & cel.Row).Value = "X"
ElseIf UCase(oFoundRng.Offset(0, 1).Value) = "YO" Then
Range("V" & cel.Row).Value = "X"
ElseIf UCase(oFoundRng.Offset(0, 1).Value) = "JAN" Then
Range("U" & cel.Row).Value = "X"
Else
MsgBox oFoundRng.Value
End If
Set oLastRng = oFoundRng
Set oFoundRng = oRng.FindNext(cel.Value) 'Getting Error(1004) here "unable to get findnext property of the range class"
If oLastRng >= oFoundRng Then
Exit Do
End If
Loop
Else
End If
Next

Answer 1

Change this line
Set oFoundRng = oRng.FindNext(oFoundRng)
to
Set oFoundRng = oRng.FindNext
You are not searching for the word but for the range you previously found. You actually don't need to pass a value to .FindNext at all.
You also have to change this line
If oLastRng >= oFoundRng Then
to
If oLastRng.Row >= oFoundRng.Row Then
since the first line compares the values (which is not what you want to do since it will always evaluate to True). You actually want to compare the row numbers.
On another note, the following code snippet does not work:
If UCase(oFoundRng.Offset(0, 1).Value) = "ISAAC" Then
Range("X" & cel.Row).Value = "X"
ElseIf UCase(oFoundRng.Offset(0, 1).Value) = "ISAAC" Then
Range("W" & cel.Row).Value = "X"
This ElseIf will never be triggered since the condition is the same as the initial If condition.
You also don't need both of these statements:
Set oFoundRng = Nothing
Exit Do
They both achieve the same thing (breaking the loop), Exit Do does it more efficiently.

Answer 2

you may be after this (explanations in comments):
Sub XMAX()
Dim cel As Range
Dim oRng As Range: Set oRng = Sheets("Sheet2").Range("A1:A7500")
Dim oFoundRng As Range
Dim firstAddress As String
With Sheets("sheet1") ' reference "Sheet1" sheet
With .Range("f4", .Cells(.Rows.Count, "f").End(xlUp)) ' reference referenced sheet column "F" range from row 4 down to last not empty one
If WorksheetFunction.CountA(.Cells) > 0 Then ' if there's at least one not empty cell
For Each cel In .SpecialCells(xlCellTypeConstants) ' loop through referenced range not empty cells
Set oFoundRng = oRng.Find(what:=cel.Value, LookIn:=xlValues, lookat:=xlWhole) ' always specify at least 'LookIn' and 'LookAt' parameters, or they will be set as per last 'Find()' usage (even from Excel UI!)
If Not oFoundRng Is Nothing Then ' if a match found
firstAddress = oFoundRng.Address ' store first matched cell address
Do
Select Case UCase(oFoundRng.Offset(0, 1).Value2)
Case "ISAAC"
.Range("X" & cel.Row).Value = "X"
Case "YO"
.Range("V" & cel.Row).Value = "X"
Case "JAN"
.Range("U" & cel.Row).Value = "X"
Case Else
MsgBox oFoundRng.Value
End Select
Set oFoundRng = oRng.FindNext(oFoundRng) ' search for next occurrence
Loop While oFoundRng.Address <> firstAddress ' exit do when hitting fisr found cell again
End If
Next
End If
End With
End With
End Sub