When posting PHP code, please use the board's [noparse]
..
[/noparse] bbcode tags as they make your code much easier to read and ananlyze.
Okay, so you call [man]mysqli_query/man here:
mysqli_query($mysql_connect, $sqlinsert)
so where is $mysql_connect ever defined? See the manual page for [man]mysqli_query/man to learn what this parameter is expected to be.