Market data access

hello , i use a simple script as below and my paper account API Key and Api Secret

from alpaca.data.live import StockDataStream

wss_client = StockDataStream(‘my_key’, ‘my_secret’)

async def quote_data_handler(data):

  print(data)

wss_client.subscribe_quotes(quote_data_handler, “SPY”)

wss_client.run()

when I start it sometimes it gives me market data quotes but sometimes not.

how can I solve the issue ?