[c-nsp] 3750 Software Joy

[Sean Granger]

show switch detail :
 
Switch#  Role   Mac Address     Priority Version  State
----------------------------------------------------------
 1       Member 588d.0967.1400     1      2       Version Mismatch
 2       Member 588d.099f.2500     1      2       Version Mismatch
 3       Member 001d.45e3.da00     1      0       Ready
*4       Master 0022.55f6.f180     1      0       Ready
 
Switch 3 and 4 are WS-C3750G-12S-E, 4 being the stack master.
Switch 1 and 2 are WS-C3750X-48T-S
 
_____
 
show version :
 
Switch Ports Model              SW Version            SW Image
------ ----- -----              ----------            ----------
     1 0     WS-C3750X-48       12.2(53)SE2           C3750E-UNIVERSALK9-M
     2 0     WS-C3750X-48       12.2(53)SE2           C3750E-UNIVERSALK9-M
     3 12    WS-C3750G-12S      12.2(52)SE            C3750-IPSERVICESK9-M
*    4 12    WS-C3750G-12S      12.2(52)SE            C3750-IPSERVICESK9-M
 
_____
 
I'm aware that the 3750X are SUPPOSED to be "backward" compatible, but when the stack master tries to load the software, it says they're incompatible system types.
 
Am I really going to have to buy an IP Base to IP Services e-license for the 3750X's just to get them into the stack?
I don't need that much heavy lifting on the copper side at all (and why they can't just be bought with an -E feature code or whatever is BEYOND me).
 
Thoughts??