Without knowing which pod and seeing your code for using the exact version, its hard to tell whats wrong.
But I'd run pod repo update
Then run pod install
This will update your local pods to the newest available versions, and then install the right pod version assuming you're setting it correctly.
Cocoapod documentation on versions:
Besides no version, or a specific one, it is also possible to use logical operators:
'> 0.1' Any version higher than 0.1
'>= 0.1' Version 0.1 and any higher version
'< 0.1' Any version lower than 0.1
'<= 0.1' Version 0.1 and any lower version
In addition to the logic operators CocoaPods has an optimistic operator ~>:
'~> 0.1.2' Version 0.1.2 and the versions up to 0.2, not including 0.2 and higher
'~> 0.1' Version 0.1 and the versions up to 1.0, not including 1.0 and higher
'~> 0' Version 0 and higher, this is basically the same as not having it.
To use the master branch of the repo:
pod 'Alamofire', :git => 'https://github.com/Alamofire/Alamofire.git'
To use a different branch of the repo:
pod 'Alamofire', :git => 'https://github.com/Alamofire/Alamofire.git', :branch => 'dev'
To use a tag of the repo:
pod 'Alamofire', :git => 'https://github.com/Alamofire/Alamofire.git', :tag => '3.1.1'
Or specify a commit:
pod 'Alamofire', :git => 'https://github.com/Alamofire/Alamofire.git', :commit => '0f506b1c45'