[Help] Problem in storing values at voucher entry.

Hello everyone,

I am using additional fields at voucher entry regarding vat calculations, but I am having an issue that my values are not getting saved like if I change the percentage of vat at stock item it will also change the vat rate at pervious voucher entries.

My code :

Code:

[#Part: STKI Basic Features]  
    Add:Part:After:STKI Units: STKI Vat
  
[Part: STKI Vat]
    Line : VAT Title, HPVat, HP Cess, HPVATRate
    Space Top: 1
    Local:Field:DEFAULT:Indent:0.5

[Line: Vat Title]
    Use:form subtitle
    Local:Field: Form SubTitle :Info: "VAT Details"
    Local:Field: Form SubTitle :Align: Left
    Local:Field: Form SubTitle :Width: 10
    Local:Field: Form SubTitle :Delete:Full Width
    Space Top: 1

[Line: HP Vat]
    Field: short Prompt, HP Vat,
    Local:Field:Short Prompt : Info: "VAT %"
  
[Field: HP Vat]
    Use: Number Field
    Storage: HpVat
    Align: Left
    Width: 10
    Format : "Percentage"
  
;;------------------------------------------------------

[Line:HP CEss]
    Field:Medium Prompt, HP Cess
    Local:Field:Medium Prompt : Info: "Add. VAT %"

[Field: Hp Cess]
    Use: Number Field
    Storage: HpCess
    Align: Left
    Width: 10
    Format : "Percentage"
  
[System:UDF]
    hpvat:Number:101
    hpcess:Number:102

;;----------------------------------------------------------

[Line : HPVATRate]
Field : Medium Prompt, HPVATRate
Local : Field : Medium Prompt : Info : $$LocaleString:"VAT Inclusive % "

[Field: HPVATRate]
Use: Number Field
Set as: #HpVat + (#HpVat * (#HPcess /100))
Set Always:Yes
Storage: RateofVAT
Align : Left
Width : 6
Format : "Percentage"

;;==================================================================================================

[#Line : EI Column One]
Add   : Right Field: At Beginning:  VatValT,AddVatT, VatIncluT
Add   : Right Field: before:VCH Rate Title : Tax Inc Titile

[Field: VatValT]
    Use:Name Field
    Set as: "VAT %"
    Width: 5
    Align: Center
    Set Always: Yes
    Skip: Yes

[Field: AddVatT]
    Use:Name Field
    Set as: "Cess %"
    Width: 5
    Align: Center
    Set Always: Yes
    Skip: Yes
[Field:VatIncluT]
    Use:Name Field
    Set as: "Inc. %"
    Width: 7
    Align: Center
    Set Always: Yes
    Skip: Yes

[#Line : EI Inv Info]
    Add: Right Field:At Beginning: VatVal, AddVat, VatInclu
[Field: VatVal]
    Use:Number Field
    Set as: $HpVat:Stockitem:#vchStockItem
    Width: 5
    Align: Center
    Style: Normal  
    Set Always: Yes
    Skip Forward: Yes
    Format: "Percentage"
    Storage: Vatper
[Field: AddVat]
    Use:Number Field
    Set as: $HpCess:Stockitem:#vchStockItem
    Width: 5
    Align: Center
    Style: Normal  
    Set Always: Yes
    Skip Forward: Yes
    Format: "Percentage"
    Storage:CessPer
[Field:Vat Inclu]
    Use:number Field
    Set as: #VatVal + (#VatVal * (#AddVat /100))
    Width: 7
    Align: Center
    Style: Normal  
    Set Always: Yes
    Skip Forward: Yes
    Format: "Percentage"
    Storage: IncPer
  
[System:UDF]
    vatper : Number: 110
    cessper : Number: 111
    incper : Number: 112