Why 2 Userforms Following the Same Initializing Mechanics Are Behaving Differently?

Question

I am creating two different userforms to amend data on a spreadsheet. Since they will be pre-populated with information on the spreadsheet, I need to initialize them before display. I was told that the initializing subs should be private. But the macro is not reading them, so I change them to public. Now, one userform is behaving fine, but the second one is still not loading. It keeps on giving the following message:

Run-time error '-2147024809 (80070057)': Could not find the specified object.

What is the error? Also, why can't I use private initializing subs like every one else? Better yet, what is a good way in managing the various userforms? Thanks!

Update after Rory's comment : There are the codes in the main module

Sub AddLog()
    AddLogForm.UserForm_Initialize
    AddLogForm.Show
    Unload AddLogForm
End Sub
Sub AmendHeader()
    AmendForm.UserForm_Initialize
    AmendForm.Show
    Unload AmendForm
End Sub

It appears that error was inside the userform sub, but I did not see it because my error trapping was not set to break inside the class module. Nonetheless, I'm still having trouble with the private/public distinction. Perhaps this snippet helps?