Input Smiley Code Adding Problem

[GoOgLe]

strText = Input.GetText("Input1"); 
cPos=GetCaretPos("Input1") 
selString = Input.GetSelection("Input1"); 
cRow=GetCaretRow("Input1") 
BeforCaret = String.Mid(strText, 1, cPos); 
AfterCaret = String.Mid(strText, cPos, -1); 
Input.SetText("Input1", BeforCaret..":)"..AfterCaret); 
Input.ScrollToLine("Input1", cRow);
Input.SetSelection("Input1", cPos+3, cPos+3);

why this code selectes wrong place after adding more than 1 smiley code ????
i think this is true;

Input.SetSelection("Input1", cPos+3, cPos+3);

[GoOgLe]

i fixed it like that but if anybody have better idea please let me know
thanks

strText = Input.GetText("Input1"); 
cPos=GetCaretPos("Input1") 
cRow=GetCaretRow("Input1") 
BeforCaret = String.Mid(strText, 1, cPos); 
AfterCaret = String.Mid(strText, cPos, -1); 
Input.SetText("Input1", BeforCaret..":)"..AfterCaret); 
Input.ScrollToLine("Input1", cRow);
Input.SetSelection("Input1", cPos, cPos);