# VALUE Error while executing UDF VBA Function on formatted cells - vba

Question

I wrote the following function to check if the prerequisites for my Excel row are satisified.
Public Function PREREQUISITESOK(prerequisites As Range) As String
Dim cw As Worksheet
Dim prerequisite_cell As Range
Dim prerequisite_cell_txt As String
Dim training_id_cell As Range
Dim no_groups_cell_to_compare As Range
Dim no_groups_cell_to_check As Range
Dim training_id_cell_txt As String
Dim training_id_cell_row_n As Integer
Dim n As Integer
Application.Volatile
PREREQUISITESOK = "OK"
Set cw = Sheets("4c.Trainings OSS")
Set training_id = cw.Range("$B$11:$B$34")
Set no_groups_cell_to_compare = cw.Range("J" & CStr(prerequisites.Row))
For Each prerequisite_cell In prerequisites.Cells
prerequisite_cell_txt = prerequisite_cell.Text
If prerequisite_cell_txt = "" Then
Exit For
Else
For Each training_id_cell In training_id.Cells
training_id_cell_txt = training_id_cell.Text
If training_id_cell_txt = prerequisite_cell_txt Then
training_id_cell_row_n = training_id_cell.Row
Set no_groups_cell_to_check = cw.Cells(training_id_cell_row_n, no_groups_cell_to_compare.Column)
If no_groups_cell_to_check.Value < no_groups_cell_to_compare.Value Then
PREREQUISITESOK = "NOT OK"
Exit Function 'It is enough for us that one prerequisite is not satisfied so we can exit the function
Else
PREREQUISITESOK = "OK"
End If
Exit For 'Training IDs are unique so if we find the right Training ID then we may exit the loop
End If
Next training_id_cell
End If
Next prerequisite_cell
End Function
Note that the prerequisites range is inline formatted.
The function that I wrote is supposed to return String value so I completely do not understand why am I getting #VALUE! error.
What is interesting that if I clear formatting from the prerequisites cells that are used as arguments of the function then #VALUE! error disappears.
Do you have any idea why this happens?