From my own experience; is the piece of hose long enough? I was trying to replace a piece of factory hose with a cut to exact length and could not get enough leverage to push it on. A friend took one look and told me it was too short. I bought another piece a couple of inches longer and what do you know, it slid right up. Sometime you just try too hard to make something work and just can't see the obvious.
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You might want try an warm up the hose with a microwaved cloth, or heat up a tapered punch an use it to expand the opening enough to slide over the fitting - an old timer taught me that one while changing out hoses in the cold. Also, make sure the metal tube is clean and the opening burr/distortion free before you try again.
Also, make sure there is no rust/corrosion present. With all of the chemicals their putting on the roads, it seems as if corrosion is everywhere.
I know this sounds simple, but been there, done it, and learned from it.
