TYPO3 - Translation doesn't show, always default language - typo3

Question

(TYPO3 loading default language instead of translation) -> same story, but I can't fix it.
I do not have much experience in TYPO3 and I have the following problem at the moment.
Standard language is Dutch and I want a French translation. I have already translated a menu + page into French.
When I click on 'FR' (French) in the language select menu, the URL of index.php? Id = 215 & L = 0 changes to index.php? Id = 215 & L = 1, but the content remains in Futch.
I have srt_languagemenu installed and configured so that when the translation is not available, the language reference in the menu disappears. This works perfectly.
When I click on 'Save and open' from the backend after I did the translation, the normal standard (Dutch) page is also shown here.
Can someone tell me what I might do wrong or forgot to set?
TYPO3: 8.7.16
Thanks!
# Language Settings
# Default Language settings
config {
linkVars = L(0-1)
sys_language_uid = 0
sys_language_overlay = 0
sys_language_mode = content_fallback
page.config.language = nl
language = nl
locale_all = nl_NL.UTF-8
htmlTag_langKey = nl
htmlTag_setParams = lang="nl" dir="ltr" class="no-js"
}
# Language Frans
[globalVar = GP:L = 1]
config {
sys_language_uid = 1
htmlTag_langKey = fr_FR
language = fr_FR
locale_all = fr_FR.UTF-8
htmlTag_setParams = lang="fr" dir="ltr" class="no-js"
}
[global]
# REALURL
config.baseURL = {$siteUrl}
config.simulateStaticDocuments = 0
config.tx_realurl_enable = 1
config.prefixLocalAnchors = all

Answer 1

Can you please provide us your Typoscript section of config. including your conditions made for those languages?
Another possibile problem: On your root page you should have declared all languages of the system. You have to make sure, that the UID of each language record equals to the number of your L Parameter in the URI or at least the config. for this language must match it.