Impact from denied entry due to having a single entry Schengen visa?

Question

I am planning to visit Spain, but I had some problems the last time I went to the Schengen area. I was issued a single-entry visa by the Swiss embassy. The agent who helped my family apply for the visa did not remind us that a single-entry visa was not valid for Croatia, even though we gave her our itinerary. When we tried to enter Croatia, the border guards said it was invalid and we should go back to Ljubljana and apply. Below is my exit stamp from Slovenia, cancelled due to the visa error. When we left the Schengen area and continued our flight to Singapore, none of the immigration officers at passport control asked us a single question.

When I took a flight from Ljubljana to Amsterdam and then Amsterdam to Athens, some of the flight attendants asked whether I had a visa. I guess it is a warning on the Schengen info system? I am worried that I might get blacklisted by the Schengen area and Croatia, as Croatia is an upcoming member of the Schengen area. I have not applied yet. I had read a blog where the writer had been denied entry due to overstaying. In my case, I never overstayed in any country. Could I have a denial of entry on my upcoming Euro trip and visa application? None of the Croatian officials stamped a denied entry or exit stamp with four lines.

Am I blacklisted or even banned from the Schengen area? Note that when I left the Schengen area via Switzerland (the country which issued me the single-entry visa and my last destination on last year's trip), not a single word came out of the passport control officer. He just stamped us out and smiled.

Here is the cancellation of the exit stamp from Slovenia, plus note that there was no letter or stamp from the Croatian border. The border inspector even said sorry and told us that if we would like to come again, we should kindly get a visa from their embassy in Ljubljana or visit another time. The Slovenian border guard just cancelled our exit stamp and asked the bus driver to drop us to the nearest bus station, and gave us a taxi number to drop us to the nearest train station to get back to Ljubljana.

Answer 1

This situation will have no effect when applying for a new Schengen visa.

You were refused entry to Croatia (at a time when Croatia was not a member of the Schengen Area) since you had used your single entry visa and therefore could not return to the Schengen Area after your visit to Croatia.

The exit stamp from the Schengen Area was canceled/voided as if it never happened.

You broke no Schengen Area rules, so no warning in the Schengen Information system will exist.