Start with Basic Troubleshooting to find out the error details.
Without knowing the error details my best guess is an issue with the .NET framework version. Site Membership Pro has packages for .NET 4.5, 4.0 and 3.5 and using the wrong one could definitely crash the site.
Since you are using mojoPortal 220.127.116.11 you definitely could not use the 4.5 .NET package of Site Membership Pro, since mojoPortal 18.104.22.168 is compiled against .NET 4. Your hosting may be .NET 4.5 but your mojoPortal installation for version 22.214.171.124 is compiled for .NET 4.0. So most likely you need to use the 4.0 package of Site Membership Pro.
Hope that helps,