Excel VBA hlookup function - vba

Question

I am trying to use the excel VBA HLookup function. I have tried it two ways and both produce error. Could anyone explain me what is that I am doing wrong?
First try:
lookupValue = Worksheets(1).Name & "!A1"
tableArray = Worksheets(3).Name & "!$A$1:$" & Col_letter & "$1"
Worksheets("Comparison").Cells(1, 2).Value = "=HLookup(" & lookupValue _
& ";" & tableArray & ";1;FALSE)"
Second try:
tda = Worksheets(1).Cells(1, 1).Value ' I also tried using tda without .Value
Table = Worksheets(3).Range(Cells(1, 1))
Worksheets("Comparison").Cells(1, 2).Value = WorksheetFunction. _
HLookup(tda, Table, 1, False)

Answer 1

For your first one, you need to use US regional settings, so a comma separator, and you should really enclose the sheet names in single quotes in case they contain spaces or look like special names (e.g. dates):
lookupValue = "'" & Worksheets(1).Name & "'!A1"
tableArray = "'" & Worksheets(3).Name & "'!$A$1:$" & Col_letter & "$1"
Worksheets("Comparison").Cells(1, 2).Formula = "=HLookup(" & lookupValue _
& "," & tableArray & ",1,FALSE)"
and for the second you have to use a range object for the table argument:
tda = Worksheets(1).Cells(1, 1).Value ' I also tried using tda without .Value
Set Table = Worksheets(3).Range(Worksheets(3).Cells(1, 1), Worksheets(3).Cells(1, Col_letter))
Worksheets("Comparison").Cells(1, 2).Value = WorksheetFunction. _
HLookup(tda, Table, 1, False)
I have assumed Table is declared as Variant, Object or Range.
Note you will still get a run-time error if there is no match for your lookup value.

Answer 2

what you're doing there usually works, which is creating a string with the function you want to call and inputting it.
I don't think that's the safest way, since it would not work if you run that macro from an Excel with a different language.
the proper way to call an Excel function from VBA call is for example:
cells(1,2) = Application.WorksheetFunction.VLookup(123,Range("A1:C100"),3,FALSE)
anyway if you'd rather use this string approach the problem in the first try is that
"=HLookup(" & lookupValue _
& ";" & tableArray & ";1;FALSE)"
results in the string:
=HLookup(Sheet1!A1;Sheet3!$A$1:$B$1;1;FALSE)
note that you're using semicolons where you're supposed to use commmas.
the problem in the second try is that the .Range property takes a string as input, so you cant Range(Cells(1,1)) you should do something like .Range("A1:A3")
hope it helps !