I am having problems receiving invitattions and sending them out. I thought that it was outlook, but after testing it out I noticed that it is not outlook. Also looked at the server and everything there looks ok. Can some one help

What are the problems? You need to be on a BES in order for the invitations to work properly.

I am also having calendar sync issues.
When I reply to a calendar invitation and click send, more often than not, I get a red 'x' on the status of the message. The red 'x' will go away after a few retries, but the person who sent the invitation will receive every response sent. My outlook sent folder also indicates multiple replies sent.
I'm on a VZW 7130e OS 4.1.0.268; BES 3.6. This started occuring sporadically about 3 weeks ago, and only occurs on my responses to calendar invites.

I am having the same issue using a BES 3.6 and 8703e devices. Another that I have noticed is that the acceptance email is actually sent, but comes back with a failed status. Also the device places two appointments on the handheld, but only one on Exchange/Outlook. If a user deletes one of the duplicate appointments they risk deleting the appointment that is stored in Exchange and missing the appointment. This seems to have occured after DST patches for us. I have verified that the CDO.dll file versions are identical on both our Exchange and BES servers. Also none of our Blackberry users have admin access.

Does anyone have any ideas on what could be causing this issue?

I'd post in the BES Admin forum as I don't think it's a handheld issue.

Make Sure that BEDADMIN has Send As rights to your exchange mailbox. Also might want to check your firewall to make sure the .dll files are allowed, this will allow the sync to happen.

I resolved this issue by installing 3.6 SP7 from their website. It seems that the cdo.dll files of late do not work well will 3.6.4 or older.