I hope I’m not wrong.

.Date.Format “2006-01-02T15:04:05Z07:00” give a string 2018-04-24T15:50:00+02:00

Is “+” not an valid XML sign???
Or is .Format wrong??
I want to get 2018-04-24T15:50:00+02:00

I found an workaround

Date**.UTC.**Format “2006-01-02T15:04:05Z07:00” give a string 2018-04-24T15:50:00Z

Any feed reader should work correct.

If you are being litteral, then you might have a slight issue since you asked for a date/time in Zone UTC+7 but are getting one in zone UTC (the trailing Z indicates Zulu time which is UTC or GMT). So you might just want to double check whether you are actually getting the correct time.