Runtime error 5

This question is probably too general, but can somebody give me an idea of what would cause me to get a

Runtime error 5: Invalid procedure call or argument?

The debugger is highlighting this line of code:
sFileName = Mid$(txtNames.Text, charOffset + 1, LineLength)

Thanks to anybody that answers :D

you must be sure that all of the vars are known in your code

VB Code:

Mid$(txtNames.Text, charOffset + 1, LineLength)

like charOffset and LineLingth

This is the entire function if it helps..

VB Code:

Public Sub ReadNames()
Dim sFileName As String
Dim Lines
Dim WinH As Long
Dim i As Integer
Dim LineLength As Long
Dim charOffset As Long
 WinH = txtNames.hWnd
    Lines = SendMessage(WinH, EM_GETLINECOUNT, 0, 0)
    For i = 0 To Lines - 1
        charOffset = SendMessage(WinH, EM_LINEINDEX, i, 0)
        LineLength = SendMessage(WinH, EM_LINELENGTH, charOffset, 0)
        sFileName = Mid$(txtNames.Text, charOffset + 1, LineLength)
        If sFileName = cboNickName.Text Then GoTo Repeat
        sFileName = Rep(sFileName, "=", "")
        sFileName = Rep(sFileName, "G,", "")
        sFileName = Rep(sFileName, "H,", "")
        sFileName = Rep(sFileName, "U,", "")
        sFileName = Rep(sFileName, "R,", "")
        sFileName = Rep(sFileName, "G,", "")
        sFileName = Rep(Rep(Rep(sFileName, ".", ""), "@", ""), "+", "")
        If sFileName <> "" Then lstNames.AddItem Trim(sFileName)
Repeat:
    Next i
End Sub

One of your arguments is invalid. Make sure charOffset + 1 or LineLength does not return any negative value.

And charOffset +1 isn't bigger than the length of your string

Ah hah!

I found out, by doing MsgBox <variables>, that

VB Code:

sFileName = Mid$(txtNames.Text, charOffset + 1, LineLength)

Is returning NULL!

Does Anybody know why it'd be doing this.

Your problem almost certainly is that charOffset + 1 is either larger than the length of your text or it is negative. To find the problem, forget msgboxes (although they can be useful in debugging sometimes) and use the debugger. If you've used the debugger before you probably know how to do all this, but here is what to do.

• Set a breakpoint on the Mid statement line by placing the cursor on the line and pressing F9
• Run the program
• When the program stops at the line, highlight charOffset + 1, press Shift-F9 and note the value. If it's negative then that's the problem.
• If it isn't then press Ctrl-g to open the Immediate window
• Type ?len(txtNames.Text), press Enter and you will probably find that the length is less then the value found in the previous step