weird situation involving last-second shot

[representing]

I had a weird situation that could have been easily avoided.

Did a JV game Saturday night. About 10 seconds left to go in the first half, A is bringing the ball up after B shot and made a basket. I am now the L while my partner is the T. I'm at the baseline of A's basket when A1 managed to lose the ball somehow (whether it was a pass-gone-bad, fumble, etc.) and B1 grabs the ball. With 5 seconds left, he runs towards the other basket to go for a right-handed layup. At this point, he is by himself. My partner (now the L) is on the left side from the basket, along the side-line at the foul-line extended. I (now the T) am running hard to get closer to see if the ball is released or not before buzzer goes of. I'm about a few feet from the half-line opposite from the basket in question, while on the right-side from the basket. The hand and ball is in clear view to me, while my partner wouldn't have been able to tell if the ball is out of the hand or not yet. At the buzzer, I saw there were a few inches between the hand and ball, so I'm getting ready to call the basket good if it goes in. The ball does go through the rim and just as I'm about to throw my hand down to say "good basket", here's my partner, who would not have had a clear view of the layup, running towards the table, hands waving off the basket, yelling "no basket! no basket!". Now, this was MY call to make, he was not in the position to make the call. We didn't have a pregame because my partner decided to show up a little late, then talk with everyone he knows on his way from the gym entrance to the official's room. So we couldn't discuss last-second shots like you would in a pre-game conference.

What do you do if you were in my situation? I was always told that in close cases like this, if one referee makes a call, whether right or wrong, without talking with the other official(s), you should not overturn that ruling, regardless of what you know is right and wrong. Following that "word of advice", I let him on his own to defend his ruling against the coach of the team he just took away two points.