If Cell Amount is Blank Confirmation Rule

A DataCell has a number of properties and functions. You are using .CellAmount but there is also .CellStatus.IsNodata so you could try something like this:

    ' Retrieve the data cell for each account
    Dim AccountPPEICSaleCell As DataCell = api.Data.GetDataCell("Cb#Consol:C#Local:S#Actual:V#Periodic:A#0710:F#PPE_ICSale:O#BeforeAdj:I#None:U1#00:U2#DEF:U3#L_UNA:U4#None:U5#None:U6#None:U7#USGAAP_FORM:U8#None")
    Dim AccountADICSaleCell As DataCell = api.Data.GetDataCell("Cb#Consol:C#Local:S#Actual:V#Periodic:A#0771:F#AD_ICSale:O#BeforeAdj:I#None:U1#00:U2#DEF:U3#L_UNA:U4#None:U5#None:U6#None:U7#USGAAP_FORM:U8#None")
    Dim AccountPPEICProceedCell As DataCell = api.Data.GetDataCell("Cb#Consol:C#Local:S#Actual:V#Periodic:A#0710:F#PPE_ICProceed:O#BeforeAdj:I#None:U1#00:U2#DEF:U3#L_UNA:U4#None:U5#None:U6#None:U7#USGAAP_FORM:U8#None")
    
    'Check if data is real data
	If AccountPPEICSaleCell.CellStatus.IsNoData = True AndAlso AccountADICSaleCell.CellStatus.IsNoData = True AndAlso AccountPPEICProceedCell.CellStatus.IsNoData = True Then
		args.ConfirmationRuleArgs.DisplayValue = 0
        Return True
	' Check if all three amounts are non-zero
    ElseIf AccountPPEICSaleCell.CellAmount <> 0 AndAlso AccountADICSaleCell.CellAmount <> 0 AndAlso AccountPPEICProceedCell.CellAmount <> 0 Then
        ' Set the DisplayValue to a meaningful string for reporting purposes
        args.ConfirmationRuleArgs.DisplayValue = (AccountPPEICSaleCell + AccountADICSaleCell + AccountPPEICProceedCell)
        Return True
    Else
        ' Indicate which accounts are zero (optional for debugging)
        args.ConfirmationRuleArgs.DisplayValue = (AccountPPEICSaleCell.CellAmount + AccountADICSaleCell.CellAmount + AccountPPEICProceedCell.CellAmount)
    End If