Solr commit returns 400 bad requests, In Log: - Unknown commit parameter 'waitFlush'

I am new to solr and I try to make one test test application when the application is running and I get an error in the visual studio at runtime, error: - solr commit returns 400 bad requests

and in the solr log file I got an error: - Unknown commit parameter 'waitFlush'

Why is this error ..

apache tomcat solr version: - 4.6.0

version of solrnet.dll: - 0.3.0.0

Solr code in .net application: -

var files = new TextFileRepository(this.connectionString).GetTextFiles();
solrWorker.Add(files);
solrWorker.Commit(); --> here i get errro "solr commit returns 400 bad request"

How to solve it ..?

Yours faithfully..