quick help with kubernetes kops

I need someone to help me sole one problem. we are using kops on AWS. Everything was good but now pods are not spinning on spot instances, but they work on on-demand instances. when we scale the ig in kops, lets say 20, it spins 20 ec2s in the AWS but but its not allocating the pods in it saying insufficient CPU. It works with on-demand ec2s. Let me know if you can help us with it. Thanks.