I was wondering why I'm having an issue modifying the table structures on existing databases at clients sites. Typically I make the modifications first on my development machine and then replicate them on the client side when the modifications are rolled out. But lately I've noticed SQL 2008 and SQL 2012 will not allow me to save the modifications on the clients servers. I receive a message indicating I will have to drop the table and recreate. Why can I make these changes on my development machine but no where else?

TIA
Jeff