Jump Start/Car died

Any reason why I would not be getting spark when I attach the ground clamp when trying to jump start a car? I have moved it all over the engine compartment, tried 2 different sets of cables and my portable battery pack. If I disconnect and reattach the neg. cable on the battery itself i do so some sparking. This came about after my 97 Blazer died without warning while sitting at a light this afternoon. I have had no issues with it stalling though i have had intermittent issues with it taking a little extra cranking to get it to turn over. Suggestions on things to look at?

Safe way? Get a multimeter, and see if the cables from the good battery are outputting 12V.

If I don't see some spark, or crackling sound, I strike quickly the 2 clamps across each other, lightly too, almost missing.

Then if the ground cable clamp is not sparking when completing the connections, then the battery (+) post is NOT connected well to the (+) cable.