In the event where you add the EasyRx integration button to a local install of Dolphin Management/Imaging (the Practice is not launching through Dolphin Cloud) and the button does not open up the browser specified in the Dolphin .ini file and take you into EasyRx, check for the following:

Verify that the path listed in the [Toolbar] section of the Dolphin.ini file is pointing to the correct location where the browser is installed.

For example, the text is probably going to read "EasyRx=EasyRx,Start EasyRx,C:\Dolphin\Buttons\easyrx.bmp,C:\Program Files\Mozilla Firefox\firefox.exe "https://app.easyrxortho.com/i/d?PatientGUID={PatientGUID}&PatientID={PatientID}&PatientFirstName={PatientFirstName}&PatientLastName={PatientLastName}&PatientBirthdate={PatientBirthdate}&NextApptDateTime={NextApptDateTime}&NextMinutes={NextApptMinutes}&NextTypeCode={NextApptTypeCode}&NextTypeDesc={NextApptTypeDesc}&NextLocation={NextApptLocation}""

which is telling Dolphin to launch FireFox from the default location (where FireFox is usually installed).

However, if they happen to be running FireFox from a different location, for instance off of a server, you would have to replace this path with the path where FireFox is installed. 

This should be the case with any browser.

To easily determine the path, you should be able to right click the desktop shortcut or Start menu item and check the Target line in the Properties.