Checking Calender items

[Kannan]

Hi,
I am trying to find the number of meetings request in the outlook calendar
using below code. But I am getting error message. The strFilter value I have
tried both "&&" and "AND" but still i am getting 'Type mismatch error
message'. Please help me what is the problem in this code.

string Appointmentline;
string[] AppointmentInfo;
string dateStart = System.DateTime.Now.AddDays(-30).ToString();
string dateEnd = System.DateTime.Now.AddDays(30).ToString();
string emailId = "", strFilter = "[Start] >= '" + dateStart + "' && [End] <=
'" + dateEnd +"'";

Outlook._Application olApp1 = new Outlook.ApplicationClass();
Outlook._NameSpace olNs1 = olApp1.GetNamespace("MAPI");
oContacts =
olNs1.GetDefaultFolder(Outlook.OlDefaultFolders.ol FolderCalendar);

MessageBox.Show(strFilter);

Outlook.Items filterItems = oContacts.Items.Restrict(strFilter);

if (filterItems.Count != 0)
MessageBox.Show("No of items found" + filterItems.Count.ToString());
else
MessageBox.Show("No items found");
return;

thanks