Help me with multimple conditional!

[COLOR=#000000][FONT=verdana]Hi there^^[/FONT][/COLOR]
[COLOR=#000000][FONT=verdana]Actually i’m trying do make that:[/FONT][/COLOR]
[COLOR=#000000][FONT=verdana]When images A and B are visibles then the image C is turn to visible too. I wrote the next script but it doesn’t work, how can I solve this problem?[/FONT][/COLOR]

[COLOR=#000000][FONT=verdana]if (imageA._visible == true && imageB._visible == true) {[/FONT][/COLOR]
[COLOR=#000000][FONT=verdana]ImageC._visible = true;[/FONT][/COLOR]
[COLOR=#000000][FONT=verdana]}[/FONT][/COLOR]