ModGen Abut Command Error

Hello,

I am trying to layout an differential input pair using the Modgen editor.

My grid pattern for the transistors for a common centroid configuration is:

B A A B

A B B A

However, when I try to abut the center transistors highlighted in bold above together, I get the following warning and the abutment fails.

*WARNING* (DBAPP-2003): Cannot find a pin figure with name 'D' on pin 'D'. In order to abut,
Layout XL requires a pin figure with a name matching the name of the corresponding pin.
Check that your pcell code assigns the correct pin name to pin figures.
If your pcells were translated from CDB, check that the strong connections were correctly translated to the
OpenAccess 2.2 connectivity model.
*WARNING* (LX-2205): Unable to abut the following two instances:
 'MP9.1' (instance of cell 'dgpfet')
 'MP9.2' (instance of cell 'dgpfet')
This occurred because the abutment function (autoAbutFET) returned nil
when called to adjust pcell parameters for abutment (event 2).
INFO (LX-1101): Ensure that this function returns 't' when successful because
Layout XL now checks the return value of the abutment function.

I have selected the CDF parameters for these devices to have Number of Fingers=1, Multiple_cell = 4. And as in the attached layout the connectivity seems to be correct.

I am using IC6.1.7-64b.500.18. Any help would be appreciated.

Thank you.