I’m not sure you gave it enough time to take effect; 30 minutes before doing the business is cutting it a bit fine.
Viagra has about an 8 hour half life and I would think you would need to wait an hour or so before the full effect kicks in. Remember though that it effects only the blood flow to your dick (it also gives me a thumping head but that’s another story) and will not effect the way you are thinking about sex; in other words you don’t automatically get aroused. If you are aroused the V should give you a nice solid consistent boner.
Cialis is a good alternative to Viagra especially as it lasts much longer (about 36 hours) and I have found it to have little or no side-effects.
If all else fails see your doctor and find get some tests. Most ED issues can be fixed easily these days if you are otherwise young and healthy.
LWH
"Louie, I think this is the beginning of a beautiful friendship"
- Humphrey Bogart to Claude Raines, Casablanca