arpeggiator stops in mainstage when i trigger a sample

Hi,

I have a strange situation, i would very grateful if some one can give me a solution.

here goes,

I,ve got mainstage 3, and novation launchKey midi keyboard, I have, on the first drum pad assigned a arp on latch mode, and a sample(loaded on playback) that plays off the second drum pad.

In the live scenario, I trigger the arp first, which plays through the song, and then when i trigger the sample on pad 2, the arp just cut off completely. it's kind of frustrating as i can't figure out how to fix this.Basically, i want the arp to continue plying while the sample kicks in...somebody help!!