Error in receiving transaction

First call 
```
await payok.get_transaction(payment=my_receipt)
```
The error is 
```
0, message='Attempt to decode JSON with unexpected mimetype: text/html; charset=utf-8', url=URL('https://play ok.io/api/transaction')
```

A random error, then it is there, then it is not there, although "my_receipt" does not change