IDOCs in status 12 not reaching the Legacy System

Hi Experts,

I am facing problem with a specific set of IDOCs in R/3.

the IDOCs are with status 12.

Queues are fine. SMQ1, SMQ2 are clear.

Also I don’t find any communication errors : (SM58 in XI)

All adapters were also working fine

<b>And in SXMB_MONI we found messages with “still waiting acknowledgement”</b>

Can anybody give me an idea about what might went Wrong.

I performed all the necessary checking but couldn't trace any errors.