Hello Seraina
The country codes of the BD-Video/DVD-Video discs are indicated with numbers (0 - 9), whereby 0, 9 and 'ALL' mean uncoded. Possibly on your medium the 'Country code A' = 'ALL'.
According to the operating instructions (page 7), the Panasonic DMP-BDT 184 can only play BD-Video/DVD-Video discs with country code 2 and 'ALL'.
Since I don't have any media with a different country code in the house, I can't test a possible codefree function. However, according to research on the Internet, there are certainly ways to play BD-Video/DVD-Video discs with a different country code using a trick.
Best regards MNuesch16

Attention! This unit does NOT play DVDs from Region 1 (USA). We bought this BluRay player because of the wrong answer here. When you want to play the DVD from the USA, the screen shows the error message "the region code of this DVD cannot be played" or something like that...