Trigger Updating Based on Same Table/Page

[LyaP]

Hi guys, I have what will probably be a simple question but I can't seem to work it out. 

Essentially I have a Checkbox called ConstructionContractAvailable? and what I would like to have happen is when a field called Prime Contractor is not blank that Checkbox will uncheck. All of this is in the same table and datapage. When I try it I get the Recursive Call warning.

All I want is when there are words in the section called Prime Contractor the checkbox unchecks itself. Is this possible?

 

I've included a picture of what I did (that didn't work). Any advice would be great. 

[MayMusic]

If  I am entering a new row and check "ConstructionContractavaiable" and add a PrimeContractor, ConstructionContractavaiable will get unchecked in the trigger below

 

Table design is :

 

 

You need to update inserted