Macpro 6,3 3rd monitor

hello thank you in advance for any input

today i hook up a 3rd monitor to my macpro 6,3. I got 1 HDMI 24inch monitor , 1 mini display port to HDMI 24inch monitor and those work fine .... i hook up a 3rd monitor on a mini display port and it doesn't detect the monitor. ive tried everything and thought it was the adapter and turned 1 monitor off and the one not working came on. lol.. crazy .. i know .. i have read that i need a Active mini display port adapter for the 3rd monitor ...any input will be welcome ..again thank you in advance

Author: @Sudden_Objective_945