can't update code

dear, below is original code and can be executed normally

def login_snow():
    log1.write_log("start login_Snow.")
    type('d', Key.WIN)
    if exists("1501554816480.png", 3):
        doubleClick("1501554816480.png")
        wait(2)

i added " wait(2) " , but failed when i click save button ,
def login_snow():
    log1.write_log("start login_Snow.")
    type('d', Key.WIN)
    wait(2)
    if exists("1501554816480.png", 3):
        doubleClick("1501554816480.png")
        wait(2)

log as below :
[error] IDE: Problem when trying to invoke menu action doSave Error: null
 can you pls help me on this ? thanks in advance