Hi,
In your case, you are intended to to procure service or an activity and not material. Since you are entered material as well as info record and hence giving an error.
Please note that external activities are not intended for procurement tangible material which does have material master data set up in the system.
Please do not enter a material and input only. Info record which has category 0 (normal) or 3 (subcontracting). Check with your MM consultant on this issue.
Thanks,
Sudhakar