Before I ever had a LD I had imagined my SG already. Now I failed 5 times finding him/her/it.
Is there a connection?
Maybe it isn’t clever to have a wrong SG in your mind.
(My imagined SG is a Snowleopard)
Instead of finding your SG, why not call out to him/her/it in your mind and wait for a response? There could be a chance your SG doesn’t wish it is the right time to see you. I for one have not met my DG or SG yet.
Welcome Flohx! 
Maybe your spirit guide may not be the way you imagined it. Try to keep an open mind, and call for him/her/it. Be ready to accept it, whatever it may be, and I’m sure you’ll have a nice meeting ^^
Hi, Flohx and welcome to the forum!
The two posters above gave some good hints. 
It’s funny, the times I’ve looked for my SC (I’ll consider SC, SG, DG, higher self or whatever to be the same…) he/she/it seemed to avoid me 
A good idea might be shouting out to the dream things like “show yourself” and then wait. If it doesn’t work, try again. And again. Things, for me at least, after a few times seem to end up working…