There are several reasons. First might be not enough information. What are the chokes? Extractors or ejectors? What are the stock dimensions? Auto safety? How much does it weigh?
You listed the gun as "good" which by the NRA/NFA condition appraisal means:
GOOD: In safe working condition, minor wear on working surfaces, no broken parts, no corrosion or pitting that will interfere with proper functioning.
Is that accurate? "Good" to me means there is some rust and pitting on the gun, perhaps stock cracks, worn checkering, etc.
From the one picture provided and it's not particuarly detailed the wood looks in rough shape particularly the forend.
Zabala is an okay Spanish name. Not one of the best but not the worst.
Also working against the gun is the configuration. The beavertail forend and pistol grip stock aren't that appealing to shooters interested in sxs.
The price is a little high for this gun in this condition and configuration.
Also you listed the gun almost a month ago and have not brought it back up so it has been pushed down by other guns.
Try bringing back to the top on the EE (no more than once a week according to the rules) and see if there is more interest. There is also no mention of shipping costs and you are in the NWT which might reduce interest as well.