Dialog window

Hi Brian,
For my project, I want to show a dialog during the execution of the routine.
I filled value to dropdown and everything as my need. 
I want to erase the text box value after an add button is clicked.
But it was not deleting the value.
DlgListBoxArray  "TextBox1", "" 
I tried with the above code. Do you have any suggestions to clear the value in textbox.
Thanks In advance