Boot mode and chaletos partition process

Dear All,
I hope this message finds you all very well,
first of all, I brought a new labtop I make it's boot mode to be legacy, and I'm running windows 8.1 on it now, then I made a 20G free space for chaletos but when I plug my live usb and once i reach to choose where to install chaletos where the installer supposed to ask me what to do, I did not found the option of installing it alongside windows so I choose something else, but it seems it want to use the whole HDD it could not see there is another OS already installed,

I kinda know i have to do something with the boot mode or there is something wrong with it because the same happend with ubuntu too it didn't show the option of install it alongside windows too.

I've opened Gparted to check on my HDD and it show this error "/dev/sda contains GPT signature, indicating that it has a GPT table, however it does not have a valid fake msdos partition table, as it should, perhaps it was corrupted possibly tables , or perhaps you deleted the GPT table and are now using an msdos partition table is that GPT partition table ? yes or no.

actually I was using EFI boot mode and I install windows on it then I switch to legacy after that by changing boot mode from BIOS option just like that wihtout using any program I do not know whither is that right or not, so what can I do now??

I did checked from windows to make sure which boot mode I'm using right now it show legacy.

thanks in advance.

I have done this many of times. I never had to manually make changes to my HHD. It did it auto. Just when it shows you the partion just slide it one way or the other till you get it sided like you want.

I'm sincerely hoping that ChaletOS 16.04 has UEFI support... it will make dual-booting so much easier

I posted your question on ChaletOS google community page and Dejan replied...

We will try to fix that but I dont have enough hardware to test all possible hardware configuration. And Yes, ChaletOS is Xubuntu, like many linux distro are same as their basic OS's. So enjoy in ChaletOS no mater what it is