There could be several reasons, including:
- Your Uphold sub account doesn’t have enough funds (e.g., BTC, USD).
- You’ve hit your exchange limit for that day, week, or month.
- You’ve placed a limit order for equities and the target price was only achieved during out of market hours. We hold a limited inventory of equities to support 24/7 trading and there are rare situations where that inventory can run out.