arc fault breaker keeps tripping

hello, i am trying to install ARC fault circuit breaker but it keeps tripping because the neutral wire that's supposed to connect to the ARC fault breaker is not dedicated but is shared with another non arc-fault circuite breaker.
Some one told me that both circuit breakers that share the same neutral wire need to be ARC Fault breaker. Even if this is true, arc fault breakers are expensive so I hope that there's another way to fix this problem.
PS I have tried running a neutral wire from the Arc Fault breaker to the neutral bus and of course the breaker still trips.
Thank you in advance for your help.

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It takes a 2-pole arc fault breaker to power a 3-wire circuit. Not all manufacturers make one.
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Long Ranger wrote:
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AFCIs include 30 ma ground fault protection. Like a GFCI there can't be a shared neutral unless a 2 pole AFCI is used as the Long Ranger said. All the current used on the circuit(s) has to go through the AFCI and add up to zero (taking into account the direction of flow).
bud--

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I have never installed a ARC fault breaker when it shares the neutral.
I assume you read the directions and called the manufactures help line.