A common factor people miss when getting this type of error is in the properties of the Daq channel name control. If it lists only the inputs, right click on the control, and select I/O name filtering. From here you will see that the analog input channels are only being displayed. depending on the type you want, select the correct type from the drop down box. The reason for this, is because of the VI type you would connect this control to. if it were an analog input VI (aquire n samples) you dont want the end user being able to select output channels to it.