Dictionary in shell script only showing last associated item

I am trying to use dictionaries and stumbled across a weird behavior. When I create a dictionary like this:

declare -A servers
servers=( ["omega"]="dev" ["delta"]="test" ["beta"]="ppd" ["alpha"]="prd" )


echo "${servers["omega"]}"

The last element "prd" will be printed to the screen, not the first one. Deleting every entry except the first one will result in the correct output. I am not sure what I am doing wrong because every code example I had a look at is using dictionaries like above. Can anyone spot my mistake? Greetings