If the hose is the same size as mine, as it appears in the picture, it will not slide over the larger barb, even if the hose is long enough. But the hose is way too large to fit tightly and securely on the smaller barb.
As I linked above, I had to remove the barbs on the larger to get the hose to fit (pretty tight) after I cut off the smaller barb.
I can only assume, hose and fixture manufacturers used different specs in the inside and outside diameter manufacturing. It appears to me the RV dealer who fixed egarant's problem ran into the same thing and tried to fix it with some sealer.
To me it is a manufacturer defect, and a DIY or a dealer tech is left to either discard the part (the hatch in this case, as the hose fit my tank fitting just fine, and probably fits egarant's) or try and use the defective part and make it work.
My solution was to cut off the smaller segment sand off the barbs on the larger.
To be frank, the hatch has some other problems in my opinion. I need to relearn then manufacturer name and avoid parts from them in the future.