Did my company unjustly denied me the $4200 I earned in commissions?

I review accounts and process over payments to the insurance carriers. I get paid a salary but also get commission. The commission is based on how much I recover against a certain budget. There is a certain section of that agreement I was told by management is the reason I was denied my commission. I read the section several times and still feel I was wrongfully denied. I was told because I had a Corrective action Plan (CAP) in the first quarter, I was not due a commission. My CAP ended on January 14, 2014, according to the last sentence of this section, I should be eligible for commission starting the days I was not on a CAP. I earned more than 90% of my paids/commissions after that date. The section also notes that if I’m on a Needs Improvement (NI) I would be denied commission, but if no longer on that NI (which ended February 23, 2014) I should be reinstated for eligibility. First Quarter was from 1/1/2014 – 03/31/2014. Section 3.3 Any Participant rated Needs Improvement (NI) or on an active Corrective Action Plan (CAP) is ineligible to receive a payout in this Plan. Therefore, any Participant on a CAP at the time incentives under this Plan are Earned (as described in Section 5.1 below) will not be eligible to receive any such payments for the calendar quarter being considered. Any payments Earned prior to the NI rating or the initiation of the CAP will be paid in accordance with Plan provisions and on the same such date other eligible Participants are 4 paid. Should any such Participant successfully meet the conditions of any such Corrective Action Plan or no longer have the NI rating, eligibility shall be reinstated on that date and only prospectively. If an employee was on a CAP for a part of a quarter, but the CAP is closed prior to the date incentive payments for that quarter are Earned, the employee may be eligible to receive a pro-rated incentive for the portion of the quarter that the employee was not on the CAP, at the discretion of management.