MacBook Pro not detecting correct external display resolution

[JerTheGeek]

I have a 2015 13" MacBook Pro and I'm trying to hook up my monitor to it, but when i plug it in, the MBP detects it as a 13.9" 800x600 monitor and looks horrible, rather than the actual 19.5" 1600x900. I am able to scale it up to a higher resolution than 800x600, but it doesn't give me the option to run it at the monitor's actual 1600x900. How can i get it to detect the monitor correctly so i can actually use it?
[doublepost=1465609731][/doublepost]Should've mentioned, its VGA to Thunderbolt that i'm using. Just ordered a DVI to Thunderbolt cable cause AC said that was my best option.

 

[jerryk]

My guess is that it is the cable and VGA, and your problems will disappear when you get your new cable. VGA is analog and always have issue with resolution. 1980s technology.

 

[JerTheGeek]

My guess is that it is the cable and VGA and you problems will disappear when you get your new cable. VGA is analog and always have issue with resolution. 1980s technology.

That's what I figured. What's weird tho is that it worked fine on my 2014 MacBook Air using same cable.

 

[JerTheGeek]

Update: got my dvi to thunderbolt cable today and it is working just fine.