Gallery2 help please

[Wossi]

I'm in the process of installing gallery2 on my web hosting but now stumped. I've got to the part where I have specify the storage setup, it says:

Gallery needs a directory to store your images. The directory we chose for you will work, but its location or current name does not provide maximum security. Either select a new directory outside of the document root directory or add a random string to the end of the directory name (e.g. g2data_16e4a64f8f).

Only problem is, no matter what I do it comes up with errors so I have no idea what to do, I'm trying to point it /var/www/vhosts/mysite.co.uk/httpdocs/gallery2/g2data_d3e4d4f5cc/ but's it's having none of it. Can someone help me out please.