Serial.println("I found strstr");
Serial.println(resultat);
should be
Serial.print("resultat: [");
Serial.print(resultat);
Serial.println("]");
Ditto for the rest of the print statements.
Once you know that resultat points to:
span id="r">145
100
54
</b
What do you want to extract from this. I thought that you were looking for the value in the "" and the value between the > and the <. The token you are telling strtok to get you is the one ending with <, or "span id="r">145". I have no idea what you expect to get from this token.
All of my code contains output statements (often commented out) that shows when a function is called, and when it ends. Yours should too.