Hardware instancing problem with Panda 1.8

Excuse me if I resume this old post, but I have another problem.
Over a number of instances (for example k = 10000) the shader gets this error:

:gobj(error): instance.cg: (7) : error C5108: unknown semantics "INSTANCEID" specified for "l_id"

I have set

 offsets = PTA_LVecBase4f.emptyArray(10000) 

and

uniform float4 offsets[10000]

Is not there a limit on instances managed by a single call?
Thanks to all.