Calling Sub from onClick event causes "application-defined or object-defined error"

Hi,

I try my best to tinker at VBA using fora like these alot. Now the "application-defined or object-defined error" is in my opinion the most vague one i've seen so far...

Basically I'm trying to call a Sub with given arguments from a UserForm dialog i created, the moment the user presses the OK button.
But everytime I run it I get the same error. The strangest thing is: when executing the line in the immediate window, it works just fine...

So here's the code(error line marked with -->):

Private Sub cmdOK_Click()
   
    Dim useCategoryFilter, useCountryFilter, useBoth As Boolean
   
    useCategoryFilter = False
    useCountryFilter = False
    useBoth = False
   
    If UserForm1.cmbCategory.Value <> "" Then
        useCategoryFilter = True
    End If
   
    If UserForm1.cmbCountry.Value <> "" Then
        useCountryFilter = True
    End If
   
    If useCategoryFilter And useCountryFilter Then
        useBoth = True
    End If
   
-->    Call ThisWorkbook.CreateChart(useCategoryFilter, useCountryFilter, useBoth, UserForm1.cmbCategory.Value, UserForm1.cmbCountry.Value)
   
    UserForm1.Hide
   
End Sub

And then for the sub(due to classified data i cannot put the whole thing, but this one runs fine, when it does):

Sub CreateChart(ByVal useFilterCategory As Boolean, ByVal useFilterCountry As Boolean, ByVal useFilterBoth As Boolean, ByVal categoryFilter As String, ByVal countryFilter As String)

'Do some stuff here

End Sub

PS.: i looked on the first 3 pages on the forum with the search line "application-defined or object-defined error" but didn't seem to find anything that is suitable for my case? Excuse me if i am incorrect on that matter.

Thanks in Advance!
Anton