Thank you all for your help on this, I can confirm the name was correct, however this is a known cisco bug for v 14.
From cisco bug search:
Symptom: After upgrading to AsyncOS version 14.x any attempt to modify content filters where the action is to add a disclaimer or notify with a specific text resource results in the below error message - Warning - The following content filters have failed to run and are currently disabled. - CONTENT FILTER NAME ["Text resource 'TEXT RESOURCE' unknown"] Conditions: ESA with content filters configured for disclaimer or notify action using text resources, upgraded to 14.x under certain configuration scenarios. Workaround: The warning appearing in the UI does not impact working of the filters. Further Problem Description: N/A