Can't open TXT file in VBA

Hello. I need some help. Hopefully it's something simple.

I am trying to open a txt file, but I get an error message that says

"Run-time error '52':
Bad file name or number

The file name is correct. I tried two ways to pass the name -- as a variable and from Application.GetOpenFilename("Text Files (*.txt), *.txt")

The line where VBA complains is "Open fileToOpen For Input As #InFile"

Function ReadFile()
Dim InFile As Integer, fileToOpen As String, strLine As String

fileToOpen = Application.GetOpenFilename("Text Files (*.txt), *.txt")

Open fileToOpen For Input As #InFile '<-- Error happens here

Do While Not EOF(InFile)
    Line Input #InFile, strLine
    Debug.Print strLine
Loop

Close #InFile
End Function

Any help is much appreciated.

Thank you,

Angel