While Posting 122 getting error M7021 "Deficit of PU GR quantity 2 EA : 1100000000 1000 G102"

Hi Experts,

While Posting 122 getting error M7021 "Deficit of PU GR quantity 2 EA : 1100000000 1000 G102".

Scenerio : Have received 4 peices of this material with Goods receipt using 105 document and want to return 2 pcs back to Vendor using 122 movement type and getting this error.

Please let me know the problem as when checked with OMCQ it is showing Warning but inspite i am getting error.

thanks