Auto Serial Number

[MdYas]

Dear Sir,

i have the formula for auto serial number with auto insert row.

i m getting problem when i click on insert new row button serial number getting changes.

please help me, and see the below formula and code for the same.

IF(COUNTA(C4:O4)>0,"01"&ROW(B4)-2,"")

Sub insert_new_row()

Rows("4:4").Select
Selection.Insert Shift:=xlDown, CopyOrigin:=xlFormatFromLeftOrAbove
End Sub