N/A means the amplification did not cross the threshold for detection before the end of the cycling. That tells me that your target gene is very low abundance.

Try doubling the amount of starting cDNA & see if that helps.

Cq of 35-36 is basically "there was a single target molecule in this well". It's usually the highest Cq value you can get before you hit "N/A".

So exactly like Katie A S Burnette says, what you have here is things like "one, none, none" or "none, one, none".

Your target is there, maybe.

Now you can use more cDNA, potentially, but PCR is exponential: you'd need to add a LOT more to substantially change matters. Twice as much would really only give you results like "none, two, one", at best.

Unless you're already using cDNA at incredibly high dilution, I don't think "adding more" will really change the conclusion that your target is there, maybe.

So you would then need to consider whether "is there, maybe" really represents a finding of biological consequence: it might be detectable, but only just, and only because PCR is incredibly sensitive. If you can barely detect it, can it really be contributing, meaningfully, to your biological scenario?

What sort of values do you see for your housekeeping gene for those samples? I gave the previous answer assuming those were easily detected.

If you see really high Cq values for the housekeeping genes, then it means that there is a different issue (e.g. degraded samples).

Do you see good amplification from any of your positive controls? What about your standard curve?