Creating alert rule: record already exists

I'm facing an issue while creating alert rule in ax 2012 r3.

Retail -> Inquiries -> Online Store Transactions.

In that form, while creating alert rule for Pending order status field. It generates the error as shown in screenshot. I've analyzed the error and found that there is no customization on this form and in Event Rule table.

Please help me asap.

Thank You,

RaviSankar