Was caught out by the fact that the maximum length of the Prompt in
Application.InputBox is much less than in the
regular InputBox. The trouble was that the error you get is Runtime error
13: Type mismatch, so I was looking at the
datatypes of the different arguments, but the trouble is not with those.
The other trouble was that this seems to be mentioned nowhere.

It looks the maximum lenght of the Prompt with Application.InputBox is 256:

Sub test()

Dim i As Long
Dim lResult As Long
Dim strResult As String

On Error GoTo PAST1
For i = 245 To 400
SendKeys "{ENTER}", False
lResult = Application.InputBox(String(i, "x"), "title", 10, Type:=1)
Next

PAST1:
MsgBox i, , "maximum prompt length with Application.InputBox"
MsgBox i, , "maximum prompt length with Application.InputBox"

On Error GoTo PAST2
For i = 200 To 10000
SendKeys "{ENTER}", False
strResult = InputBox(String(i, "x"), "title", "a")
Next

PAST2:
MsgBox i, , "maximum prompt length with InputBox"
MsgBox i, , "maximum prompt length with InputBox"

End Sub


Haven't found the maximum yet with the regular InputBox, but it is much
more.

Is this is a known problem? I suppose it is.
Is there a workaround? I suppose not.


RBS