It happened a few times that customers got this message when they have scanned perfectly valid ticket. At the same time, if the ticket was scanned with Android or iOS device, check-in was successful which got them pretty puzzled what might be happening.
This typically occurs when barcode reader device is used to scan the barcodes from the tickets. What is important to understand here is that barcode readers are basically HIDs (human interface devices) and are much like any keyboard. The key difference, of course, is that instead of entering values by keys, barcode readers are scanning the barcode, decoding it to plain text and then entering it, the same way it would be entered with any other keyboard. With that in mind, you can conclude that the keyboard layout plays significant role here. So, for example, if you set the keyboard layout to, say, German, French or some other "non standard" layout, you will notice that certain symbols are located on different keys on the keyboard than when English keyboard layout is used. And this, actually, is the key of this problem. Most ticket codes in Tickera, by default, contain a dash "-" symbol which is perfectly recognizable by barcode scanner. However, if the keyboard layout set on the computer to which you have your barcode scanner device connected is using some non-typical keyboard layout, it is likely that this dash symbol will become "something else" purely because of the keyboard layout.
Okay, to identify this issue, first open some plain text editor on the computer that has your barcode scanner connected (Notepad, TextEdit or anything similar). Now, scan the ticket and see what the result is. If the text that will be entered to the text editor is different than the ticket code (barcodes are generated based on the ticket codes), then it can't be recognized by Checkinera app and it will return Wrong Ticket Code response. Try now to change the keyboard layout on that same computer to English and then scan the barcode from the ticket again to that same plain text editor. It is very likely that the result will be now a perfect match with the ticket code. If that is the case, you can close the plain text editor that you have used for testing and start Checkinera app and start scanning the tickets without any problems.