Messages mysteriously dissappearing in PI

Hello friends

We have few interfaces (using JMS adapter) which are being successfuly used on a daily basis. Per day about several thousand messages pass through these interfaces successfully. However, the recipients keep complaining that every now and then they don't get few messages (may be 3-4 a week).

I have checked for the particular messages that they say are missing. But I can see those messages getting processed in PI successfully. I have checked both SXMB_MONI and RWB.

I have done lots of research on internet and haven't found any solution.

We use PI 7.1.

Has anybody seen this problem before? I would appreciate any feedback on this.

Hope to hear from some one soon.

Thanks

Ram