Often it appears if the conditional statements are not working properly - here is why:

When using either the MATCHES or DOESNOTMATCH operator the value attribute is a Regular Expression so one needs to be mindful that any REGEX metacharacters must be escaped for the operation to work as intended
   
Following on from the MATCHES or DOESNOTMATCH discussion above one needs to be careful when setting the value attribute in the condition to extract its contents from another field in memory using the ~#~ notation for example ~#~MyField~#~. This field may contain a REGEX metacharacters in which the case the operation would not behave as intended. To get around this issue you would need to apply the MD5Hash rule to both fields that are used as the operands in the condition

The eq, lt, gt and ne operations ONLY work on NUMBERS