"Hide Object When" requires an Expression that evaluates to a Boolean value so
YOurTable::CRType = "addition"
would be such a Boolean expression allowing you to specify that a layout object be invisible when the CRType field of the current record is "Addition".
This sounds like you might be able to use a trick known as the hidden tab panel. Essentially you set up tabs that have crtype specific fields on each tab. Give the tabs object names. Shrink the tabs to make them disappear, and use script triggers to go to the right object /tab by name (under the right conditions).
In FileMaker 13, the "Hide Object When" setting is much simpler to implement than a hidden tab panel--one of several "hide the object" tricks we use in versions prior to 13.
Thank you both for the response. PhilModJunk's suggestion worked great. Thanks again for the quick responses!