Assigning macro to shape

Hello, can anyone tell me what's wrong with this code:

Worksheets("----MAIN----").Shapes.Range("TextBox 77").OnAction = "CANCELCHANGES"

also've tried:

Set tempSHP = Worksheets("----MAIN----").Shapes.Range("TextBox 77")
        tempSHP.OnAction = "CANCELCHANGES"

Thanks in advance!