The version number of the external content type you are trying to save is lower than the version number in the Business Data ...

The version number of the external content type you are trying to save is lower than the version number in the Business Data Connectivity Metadata Store. The external content type may have been updated since you started editing or you have lowered the version number manually. To save now, make sure the version number is higher than the one in the Business Data Connectivity Metadata Store. Saving will overwrite any changes that may have been made by another user.