Well, thats all true, but a few other typical culprits.
Firstly, a cheap fix for frozen transforms, is to create a locator with matching position to your model...which SHOULD be the origin if you have been behaving with your modelling. Then snap it to the centre of your blendshape1. Then make a note of the transform. Then you can snap your blendshape back to the origin, re-freaze the transforms, and snap it back to the locator, or type in your locator transforms. Should all be hunky doory now.
Now, if your transforms are not causing the problem, though they probably are, the other two things to be aware of is :
1) if you have added or removed isoparms form the original or from the blendshape, it ain't gonna work. You need the isoparms U and V to match. If you had to add isoparms, you will need to add more to the other model to match. Use the attribute editor to get the isoparm info. Once you have done that, your isoparms will be dirty and are probably already mis-matched from the original. So, use the rebuild surfaces tool with the 'keep' 'cvs' ' UandV' all turned on. So all it will do is re-preamiterize the surface, shifting the isoparms to fit evenly and therefore match, without loosing any of the sculpting you have done.
2) And most importantly...make sure your blendshapes are NOT skinned to your skeleton setup, and are NOT in the same hierarchy as the target shape. Keep em as a seperate group well seperate from the main character set/group. If you have your blendshapes in the hierarchy with the target shape, it produces double deforms within local space, hence, the target appears to fly off of the position when blending, cos it is trying to match the cv's to local space positions within the same hierarchy....effectively, like matching to world space. Not what you want. so don't do it.
Now heres a little tip if you don't know it already. Try to use local defs as little as you can, i.e. try to avoid shifting cv's by hand as much as poss when making blendshapes. And use bones is really not a terribly controolable way to do it either. Best tool for making blendshapes without loosing surface integrity and without requiring extra isoparms, and maintaining transforms, is to just deform the bldnshape with a medium-heavy lattice. Medium heavy cos you don't want to loose the edges that match into other patches, but you don't want messy overlapping interpolation of the shape within the lattice. So, not too heavy, but not too light.