The Sims 3 Compatibility Error

"The Sims™ 3 High-End Loft Stuff Compatibility error - The version of The Sims™ 3 installed is not updatable and is not compatible with The Sims™ 3 High-End Loft Stuff." I am running a MacBook that meets all of the requirements and then some, I already have The Sims 3, and the World Adventures Expansion pack installed and they both work great. I received the High End Loft expansion pack as a birthday gift and absolutely cannot get it to install. My game has the latest patches, updates, etc. Glitches here and there, sure - but this is ridiculous.

Is anyone else having this problem/has anyone found a solution?

Hardware Overview:

Model Name: MacBook
Model Identifier: MacBook5,2
Processor Name: Intel Core 2 Duo
Processor Speed: 2 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 2 GB
Bus Speed: 1.07 GHz
Boot ROM Version: MB52.0088.B05
SMC Version (system): 1.38f5
Serial Number (system): W8916B4K4R1
Hardware UUID: 8DDECFDF-4B61-5ECD-8466-0199623E4AA7
Sudden Motion Sensor:
State: Enabled