I don't think the category guids for resolution categories and incident catergories will ever match. As they are from different category lists. I think you will have to link the tables using the categroy title or name fields.
Based off the default joins that crystal uses and the since the guids wont match as someone has already said, this should return nothing.
I've got a lot of good information and trending out of crystal through trial and error so if you explain the type of report you're looking for, maybe we can help.
As far as your category report, I would right join im_incident_category.im_guid --- im_incident.im_category_guid
I would then left join im_incident.pm_guid --- im_incident_resolution.im_incident_guid
then left join im_incident_resolution.im_category_guid --- im_incident_resolution_category.im_guid
then Id drop im_incident_category.im_full_name and im_incident_resolution_category.im_full_name to compare each tickets category vs. resolution category.
I dont know what fields are mandatory on your incident and if you do not have every category filled in for resolutions and incidents, this will drop a lot of incidents under the default joins.
As has been mentioned before, the Resoution and Incident categories are not the same thing, even if they're titles match the GUIDs will not, so you would need to add both of these fields in.
You JOINS would be from Incident to Incident Category and from Resolution to Resolution Category. As for the Location Code, some of your earlier incidents may not have a selected location so the default INNER JOIN Crystal would select wouldn't work. I've found with these the easiest solution is to set the link type to LEFT OUTER JOIN and ensure the reference list (in this case Location) is on the left side of the JOIN.
This may also impact your Resolution Category joins. If every Resolution doesn't have an associated Category you will likely fall into a similar situation, so again you can use LEFT OUTER JOIN to correct this. This may not necessarily be best practise but it is the simplest solution I've found. Hope this helps.