I would really appreciate if someone out there could help me find my way out of this. I have done a few westerns for renin extracted from mice kidney and was able to obtain some bands.
However, of recent , using the same protocols and same conditions ,I have struggled endlessly to reproduce the the result.Please can somone tell me what might be the problem as i have checked all my reagents, even made new stock and still got nothing. Please HELP!!!

Are you still loading the same amount of total protein on the gels and are you sure the antibody is still working (did you have a positive control such as recombinant renin loaded next to your samples?)

Another variable could be the animals. Either age (older animals producing less renin) or hypertensive state.

i will make sure that
1. the 1st antibody is still good
2. the 2nd antibody is right
3. the detection method is right for the 2nd antibody.

it happened to me before that the 2nd antibody in the box which used to be HRP linked had been reordered as AP linked with no notification, and wasted me 2 weeks

and one more thing, if you are using chmiluminence, check the regent, they go bad pretty easily