Function Callback - panel ID

I use a button on one tab to change the content of textboxes with one on another different tab.

int CVICALLBACK cbfGetIP (int panel, int control, int event, void *callbackData, int eventData1, int eventData2)
{
    switch (event)
    {
        case EVENT_LEFT_CLICK:

            ResetTextBox   (panel,   tabPanel1_Textbox_1,   "AAA");   //current panel, works

            ResetTextBox   (panel,   tabPanel2_Textbox_2,   "BBB");  //other panel, not work

            break;
    }

    return 0;
}

The second line where the textbox on the other tab is does not work.  the ID of the panel is not good.  I use debugging to obtain the integer that make it work.  Problem: that number does not correspond to anything resembling that is the tab number.  Of course, I do not want to be amateur using integer this way.  Can someone explain this to me?  Thanks.