Angola 2 kwanzas - incorrect / missing date

Please refer to the below link. I've got a 1975 coin (the picture date in 1975) but there is only a date for 1977. It will not allow me to correct it. Thanks, Janine

https://en.numista.com/catalogue/pieces4562.html

 That is the correct coin.
On the obverse it reads  11 DE NOVEMBRO DE 1975  but that is not the coin date. It is the date which the coin commemorates; on that page it says against 1977 that there are 'no date letters' on it. I read that date in 1975 is when Angola gained its independence (from Portugal). Hope I got all that right.  

Thanks ZakUK - I'll have to assume that my coins date in 1977 commemorating 1975... I have added it in.

 There are a few other Angola denominations around that time that also have no 'date' on them. Similar happened to Jersey with a commemorative date but not mintage date ...
https://en.numista.com/forum/topic5553.html

 Also, how has your first month on here been (I see you joined 10-Jan).