Barcode Code 128 Issue

I'm afraid we need more information, because your snippet of code is not sufficient to reveal the problem. It is more likely that somewhere else in the program a variable has not been properly declared and initialised. In your function, however, you should consider using a while...wend loop rather than a for...if...then...exit for...end if...next construction, as that will deal with any number of occurrences of search text, and look much tidier.

As suggested by #1

I guess that the For … next might be limiting the number of occurrences of the string you are searching. Maybe you have reached a point where the serial number being converted has some kind of occurrence that is more than 10 or a character that is not taken care of in the string to be searched, therefore giving a wrong code???

To replace the for next with a Do … Loop -à

Function ReplaceStr(ByVal Origstr As String, ByVal Searchstr As String, ByVal ReplStr As String) As String
'Exchanges all occurrence of searchstr with replstr in origstr

'Here Searchstr is BARTEXT mentioned in .prn file whereas ReplStr is the serial no generated thru the program
'
Dim pos As Long
Dim i As Integer
Dim first As String
Dim last As String
'
' Origstr = ""

pos = InStr(pos, Origstr, Searchstr)

Do while pos > 0

first = Mid$(Origstr, 1, pos - 1)
last = Mid$(Origstr, (pos + Len(Searchstr)), (Len(Origstr) - Len(first) - Len(Searchstr)))
Origstr = first + ReplStr + last

pos = InStr(pos, Origstr, Searchstr)
Loop

ReplaceStr = Origstr 'Replace string with original data

End function

==== The loop will find all the occurrences even if more than 10 and will return if none is found ===============

More than that I cannot help without the remaining of the code.

I can only correct the logic of the code as far as I can guess what you are doing.

er.haven't meet this kind of problem,but you may look at the article about barcode 128