Error Message Help - Functionality

Listed below are a series of functionality errors along with the screenshots and brief explanations:
Error creating receipt  – This error appears when the merchant account is not properly configured within the Groovv Register Application on your Android device
Network Printer Error
Bluetooth Printer Error
USB Printer Error
CC Error - The micro USB credit card swiper is unable to return value to a credit card. To perform a return a transaction must be associated. To perform these actions visit Transaction Detail or Transaction Lookup.
You must select a Table before starting a transaction - In order to begin placing an order, a table must first be selected and opened using the Table Select screen
Press [Server] button to log on first - Require server to login before a transaction has been enabled via System Data
Invalid Pin Entered - The incorrect PIN has been entered as a server/manager
Clerk not Active - Clerk profile has been marked inactive and can no longer log into the Groovv Register application
Discount cannot be greater than subtotal - The value ($) discount can not exceed the total receipt subtotal
Error:java.lang.NullPointerException – 2 Potential Reasons for this:
You're tablet's screen is less than 10", in which case you must go to Settings, and switch to [Widescreen] orientation.
No apps can perform this action - unable to email reports from Register Options Menu > Reports because there is no app with the ability to send emails
Error processing discount.  Can’t find last transaction. – Error applying % discount while logged in as a clerk in Training Mode.
Invalid Email - Email can not be used without error sending emailed receipts
Invalid Email - Invalid email applied to a customer profile created on the tablet. Shown from the Finalize Screen.
Invalid Email - Invalid email applied to a customer profile created in the Back Office