Abstract. The above-titled paper of mine appeared in the Acta Sci. Math. (Szeged), 71 (2005), 159--174. Regrettably, the proof of our main result contains an error which we want to correct here.

AMS Subject Classification (1991): 40C10, 42B10

Received August 15, 2006. (Registered under 5949/2009.)