Not making spark on sr20

[nissan505]

So I just installed an sr20 red top in my 91 hatch and when j go to start it sometimes it will start right up and others ot will crank with out making any spark wondering what should I do and what I might have missed please help

[onehundredoctane]

Check ECU connection to harness, if it isn't really tight sometimes you can get odd problems like this.

Test CAS.

Check grounding for coil packs.