1. Ensure that they have the default instance registered - 

dsmqver should have a primary instance set to Yes if not

setmqinst -n Installation1 -i

2. run c:\program files (x86)\websphere mq\bin\amqiregisterdotnet

4. put the client dll's 

amqmdnet.dll and amqmdxcs.dll into the executable directorys namely c:\program files (x86)\mqattach\mqaweb\bin and c:\program files (x86)\mqattach\mqalauncher\

3. restart the machine