Hi,

I have never loaded cDNA on a agorose gel, only PCR products. Are you sure that you have sufficient material loaded (what was the concentration of cDNA in 1 µl), maybe there is a detection limit. What was the CT-value in your qPCR experiment (in the range of 20 - 30 or 38 suggesting low input material (especially for the house keeping gene). I would suggest that qPCR of cause, is much more sensitive than agorose gels. 

Hi,

cDNA appears as a smear on an agarose gel however visibility depends on RNA concentration used.  

No bands or faint bands could mean that your cDNA is just too small to be visualized in agarose gel. In this case you could try to run it on more concentrated gels, like 3%.

I do think that after rt-PCR amplification the amount of cDNA is enough for an agarose gel, by the way you can check by runnunig the housekeeping gene amplification product as well, they are usually more expressed then any GOI

As Satti says: cDNA would appear as a smear, if it appears at all.

You've essentially copied all your RNA to single-stranded DNA molecules of wildly varying lengths. You wouldn't expect a band from this, unless you used total RNA and random priming, in which case you might (possibly) see two smeary ribosomal bands. 

Remember: DNA of sufficient concentration to be visible on a gel represents a truly ridiculous number of molecules, whereas PCR can amplify as little as a single transcript. You don't need to be able to visualise your cDNA to know it's there, nor would I recommend doing this anyway (it doesn't tell you anything useful).

If your qPCR is working fine, then your cDNA is probably fine.