MLG CLB TO OCCUPIED ALT HAD LTSS FROM LTT. SYS ERROR.

Narrative

I WAS WORKING THE RADAR POS ON SECTOR 5. THE TFC COMPLEXITY AT THE TIME WAS 4 OUT OF 5 ACFT WERE DEVIATING BECAUSE OF WX AND THERE WERE RPTS OF MODERATE TURB BELOW FL260. THE SECTOR TO THE S OF SECTOR 5 HAD HOLDING ACFT DEVIATING INTO SECTOR 5. I HAD AN SMT WBOUND AT FL260. THE SMT NEEDED TO DEVIATE FOR WX AND WOULD NOT DEV N. I APPROVED A S DEV FOR THE SMT. I ALSO HAD A JET ARRIVING AT ASPEN FROM THE E THAT I WAS TRYING TO DSND. 3 DENVER DEPS CLBED OUT WBOUND. I CLRED THE FIRST 2 TO FL250 BECAUSE OF THE SMT. THE THIRD DEP WAS AN MLG BEHIND AN LTT. I CLRED THE MLG TO FL250 AND TURNED 20 DEGS R FOR CLB. THE MLG HAD TOO MUCH OVERTAKE ON THE LTT. I RECOGNIZED THE OVERTAKE BUT THE MLG WAS ALREADY ABOVE FL240 WHEN I AMENDED HIS ALT TO FL240. SUPPLEMENTAL INFO FROM ACN 214497. MLG LEVEL AT 230; CLRED TO 250 BY ATC. CLB WAS RAPID DUE TO DESIRE TO TOP BUILD-UP IN AREA. AS MLG NEARED LEVEL-OFF AT 250 (OUT OF 24800); CTLR RECLRED FLT TO 240; WITH 'EXPEDITE.' MLG RETURNED TO 240 WITHOUT INCIDENT. BOTH CAPT AND FO RESPONDED ALOUD TO CLRNC FROM 230 TO 250. FO READBACK '250' TO ATC.