Does anyone know what would cause this error?

unknown transmission status: sequence out of order

I get it when I execute the following oAdatapter.Fill(oTable) statement. Sometimes the code works, sometimes it does not.This is the SQL I am using:

"SELECT Task.*, Activity.*, Category.CategoryName, Logon.LogonName AS AssignToName FROM Task, Activity, Category, Logon WHERE Activity.ActivityID = Task.TaskID AND Task.CategoryID = Category.CategoryID AND Task.AssignToLogonID = Logon.LogonID AND IsNull(ActualCompleteDate) AND ((TargetStartDate>='2004/2/27' AND TargetStartDate<='2004/2/27') OR (TargetCompleteDate>='2004/2/27' AND TargetCompleteDate<='2004/2/27') OR (IsNull(ActualCompleteDate) AND (TargetStartDate <'2004/2/27' OR TargetCompleteDate <'2004/2/27'))) "

oDataAdapter = New MySqlDataAdapter(sSQL, ConnConfigDB.GetTEAMConnectionString)