I contacted the company where I bought the NUC (I bought the NUC and hardware from seperate vendors) they assured that those RAM (gave them the serialnumber) should be compatible.
I bought the exact same RAM from the company where I bought the NUC (inorder to verify if the problem was with the NUC or the RAM) and they worked perfectly.
It turned out that both sticks of ram I bought initially was faulty.
Thank you for sharing this information. I am glad to hear that you were able to resolve your issue.