installing an x display manager to a cli version of ubuntu.

[J05HYYY]

Hello, I have downloaded a command line version of Ubuntu so I can install everything I want almost from scratch. Problem is, when I install an x display manager it wont let me login. It just flashes for a second with a cross, then returns back to the login screen...
stuck in a loop.

"sudo startx" works but not "startx". I have tried lxdm and xdm.

Please help.

[J05HYYY]

I realised that there was not enough space on the hard drive for either one to run.