shape keys

Hi
I’ve a anim that goes from 1-300 with keys in the dope sheet as well as shape keys. Now what I want is to delete keys 298-300 and add a animation from 298-400.
In the vids I’ve seen so far you can only add one shape key in 298 and 400. Now the value should move between those two? Why has the autor previously created 300 keys?
Many thanks

Without a blend file, or screenshots, or something, your question doesn’t make sense.

Well got it working, now how to get rid of the color difference. Removing doubles etc. no luck so far. Thanks