That's great advice Fran.I'd check the drain plug as Don said, it could be same mfg. Better than putting it on and have problems.
To find leaks water isn't the best because surface tension. You can fill a glass of water if done carefully it will above the top of the rim of glass. Gas or lacquer thinner works well. The pan OP ordered doesn't have seams, just checking drain plug so he won't have the problem you had.Easiest way is probably just fill it with water.