PO not updates in ICH due to table entry error

Hi Experts,

I have an issue while sending the PO from R/3 to SNC. Below error has occured and not able to understand what exactly this error. I have checked the PO data and everything is correct in R/3.

"Error changing a table entry (secondary index /1OM/ORDR7MP3100, mode M)"

Could you please help me to resolve the issue as many PO's are blocked due to above error.

Regards

Gowri